CN100514071C - Shunt circuit linearity insulating circuit apparatus - Google Patents
Shunt circuit linearity insulating circuit apparatus Download PDFInfo
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- CN100514071C CN100514071C CNB2006101547389A CN200610154738A CN100514071C CN 100514071 C CN100514071 C CN 100514071C CN B2006101547389 A CNB2006101547389 A CN B2006101547389A CN 200610154738 A CN200610154738 A CN 200610154738A CN 100514071 C CN100514071 C CN 100514071C
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/04—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only
- H03F3/08—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light
- H03F3/085—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light using opto-couplers between stages
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/261—Amplifier which being suitable for instrumentation applications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/273—Indexing scheme relating to amplifiers the DC-isolation amplifier, e.g. chopper amplifier, modulation/demodulation amplifier, uses inductive isolation means, e.g. transformers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/276—Indexing scheme relating to amplifiers the DC-isolation amplifier, e.g. chopper amplifier, modulation/demodulation amplifier, uses optical isolation means, e.g. optical couplers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45138—Two or more differential amplifiers in IC-block form are combined, e.g. measuring amplifiers
Abstract
This invention relates to router linear isolation circuit device, which comprises transducer, photoelectricity isolation amplifier and signal combination device and one abstract frequency and one time parameter adjust circuit, wherein, the abstract frequency device is composed of low band filter and high band filter and one abstract device; the input signal is connected to low band filter or high band filter input end and first input end of abstract device; the low band and high band filter output end is connected to other end of abstract device.
Description
Technical field:
The present invention relates to electronic metering equipment, more particularly, relate to a kind of linear (or two-way) buffer circuit along separate routes, this circuit has stable and the flat frequency response, can carry out the electric signal voltage measurement in very wide frequency range isolator.
Background technology:
Buffer circuit can arrive outgoing side with the electrical signal transfer of input side, but isolates on electric between input side and the outgoing side, insulate in other words conj.or perhaps, only has a less electric capacity between input side and the outgoing side.
Buffer circuit can improve the common-mode rejection ratio when measuring, and reduces and disturbs, and improves signal quality, also can completely cut off dangerous voltage, protection equipment and personal safety.When hyperchannel was measured simultaneously, buffer circuit can also prevent the short circuit accident that causes altogether because of interchannel.
From processed signal, buffer circuit can be divided into digital buffer circuit and linear or simulation buffer circuit.The numeral buffer circuit is only handled high and low level signal, and normally 0V and 5V signal belong to switching signal, technical easy realization.Circuit linearity insulating circuit is commonly referred to isolated amplifier, and its output signal and input signal are linear, can transmit simulating signal.Technical difficult realization of the circuit linearity insulating circuit of high bandwidth (more than the number megahertz).
Realize because numeral is isolated easily, analog input signal can be carried out mould/number conversion earlier, become digital signal, carrying out numeral then isolates, D/A switch obtains analog output signal again, realizes that so easily the simulating signal of stable high linearity and high bandwidth is isolated.But this technical scheme circuit complexity, cost is higher.Though input signal and output signal all are simulating signals, this method is that numeral is isolated in essence.
Of the present invention to liking the wide-band linearity buffer circuit.
From the medium of signal transmission, the method that signal is transmitted in common isolation has by magnetic field, electric field, these three kinds of methods of light transmission signal.
The typical element that transmits signal with magnetic field is a transformer.To the isolation of AC signal, can directly use transformer.But transformer can not transmit direct current signal, the signal very low to frequency, and excitatory reactance becomes very little, and transmission effect is also bad.To transmit direct current and low frequency signal with transformer, must input signal be modulated into an AC signal, transmit this signal with transformer at input end, in the output terminal demodulation, obtain one with the linear output signal of input signal.Typical circuit has the AD215 series isolated amplifier of U.S. AnalogDevices company, and isolation voltage ranges up to 2500Vrms, and nonlinearity can reach 0.005%, and the signal band width ranges up to DC-120kHz.After adding the modulation and demodulation link, the frequency band height that is not easy to do.
The typical element that transmits signal with electric field is an electric capacity.Electric capacity also can only transmit AC signal, can't transmit direct current signal, the AC signal lower to frequency, and it is very big that capacitive reactance becomes, and also is unfavorable for transmitting.To transmit direct current and low frequency signal with capacitor, must input signal be modulated into an AC signal, transmit this signal with capacitor at input end, in the output terminal demodulation, obtain one with the linear output signal of input signal.For good isolation effect is arranged, capacitance should be very low, usually below the number pico farad.Typical circuit has the U.S. Burr-Brown company ISO124 series of (now having incorporated U.S. Texas Instruments company into), and isolation voltage ranges up to 1500Vrms, and nonlinearity can reach 0.01%, and the signal band width ranges up to DC-50kHz.After adding the modulation and demodulation link, the frequency band height that also is not easy to do.
Using up the typical element that transmits electric signal is photoelectrical coupler (abbreviation optocoupler).Different with above-mentioned two kinds of methods, can directly transmit direct current and low frequency signal with optocoupler, do not need to be modulated into AC signal.Early stage optocoupler mainly for isolating the digital signal design, for the isolation mode analog signal, need add peripheral circuits such as operational amplifier, makes LED and photoelectric tube in the optocoupler be operated in linear condition.This kind buffer circuit structurally is divided into two kinds of non-feedback-type and feedback-types.Non-feedback-type adds an optocoupler by two operational amplifiers usually and forms, and the linearity is relatively poor.Feedback-type adds two optocouplers by two operational amplifiers usually and forms, and wherein an optocoupler is as feedback compensation, and the linearity increases.The linear optical coupling that had occurred linear isolation special use afterwards, its structure are that a LED and two photodiodes are integrated in the encapsulation, and wherein a photodiode is used for feedback compensation, and the another photodiode is used to transmit signal to outgoing side.Typical linear optical coupling has the LOC110 series of U.S. CLARE company, the IL300 series of U.S. VISHAY company, and the nonlinearity of these two kinds of optocouplers can reach 0.01%, and bandwidth can reach DC-200kHz.The HCNR200/201 linear optical coupling of U.S. Agilent company has been expanded bandwidth, can reach DC-1MHz.
Also there is document to introduce the circuit linearity insulating circuit of DC-4MHz bandwidth.
By above-mentioned introduction as seen, the multipotency of ready-made single mode circuit linearity insulating circuit is operated in the frequency band of DC to number MHz.For high bandwidth more (as DC to tens of million or hundreds of megahertz) signal, foregoing circuit can't realize that linear the isolation transmit.
Notice that foregoing circuit can realize preferably that the linearity of the signal from direct current to hundreds of KHz isolates, and can directly realize from low frequency (thousands of hertz) to high frequency the linearity isolation of the AC signal of (tens of million or hundreds of megahertz) with transformer or electric capacity, if both can be made up, just can realize that the linearity from direct current to hundreds of megahertz bandwidth is isolated.So-called shunt that Here it is (or two-way) circuit linearity insulating circuit.It is made up of direct current tremendously low frequency passage (abbreviation low path) and low frequency tremendously high frequency passage (being called for short Gao Lu).
Because circuit complexity, the time delay of modulation-demo-demodulation method are big, so low path generally selects for use linear photoconductor to isolate.And high road with transformer than realizing easily with electric capacity.
Isolate for realizing split-path linear, at first input signal must be resolved into low path and Gao Lu two parts, then, isolate through photoelectricity channel isolation and transformer channels respectively, at last with two passages signal plus, obtain the output signal linear with input signal.
There are two difficult points in this method.
First difficult point is that signal decomposition is become low path and Gao Lu two parts.The frequency divider that uses low-pass filter and Hi-pass filter to form traditionally resolves into low path and Gao Lu with input signal.But will can not go back original input signal faithfully after the output signal addition of two wave filters, near the crossover frequency of high-pass and low-pass filter, amplitude-frequency response exists salient point or concave point, and the phase-frequency response of entire circuit is not linear, therefore the output signal square-wave response is poor, can not be used for broadband signal and measure.For this reason, need to add complicated compensation and regulating circuit, improve circuit amplitude-frequency response and phase-frequency response.This has caused this kind broadband isolation circuit cost height, complicated, the poor stability of debugging.Typical products such as the early production A6902B of U.S. Tektronix company.
The time-delay that second difficult point is low path channel isolation and Gao Lu channel isolation is inconsistent.High paths is handled the signal of the paramount frequency range of low frequency by transformer isolation, and it is little to delay time; Low paths is isolated by photoelectricity, handles the signal of direct current tremendously low frequency section, postpones long.Even first difficult point does not exist, the inconsistent output signal that still can cause synthesizing of the time-delay of low path and Gao Lu can not be gone back original input signal, and its phenomenon is that the top is recessed near the square-wave response forward position.For this reason, need to add delay circuit, as described in " electrical measurement and instrument " paper of 2004 the 6th phases of magazine " design of wide-band isolated amplifier of dual path " literary composition on high road.Delay circuit makes also that circuit cost improves, bad stability, and has spinoffs such as the uneven and phase-frequency response of amplitude-frequency response is non-linear.
For overcoming above-mentioned difficult point, patent ZL96101007.X has proposed a kind of in direct current tremendously low frequency section, utilizes the output signal of photoelectric isolating circuit that transformer is carried out the broadband two-way circuit linearity insulating circuit that magnetic flux returns to zero.But the transformer in the method is complicated, and, when low path and high road signal amplitude not during matched well, in the magnetic core of transformer direct current flux may appear, and can cause magnetic core saturated or magnetize, moreover the common mode inhibition of its photoelectric isolating circuit under high frequency is lower.
Summary of the invention:
The invention provides a simple shunt circuit linearity insulating circuit apparatus, this device can be exempted complicated frequency compensation adjustment and delay compensation adjustment, has very wide signal measurement bandwidth, and total cost is lower, and higher reliability is arranged; In very wide signal measurement frequency range, all have accurately and reliably and respond; The shunt circuit linearity insulating circuit apparatus of this kind simplification can be kept stable frequency and impulse response, only needs simple frequency response compensation adjustment, need not to add delay circuit on high road, also need not in direct current tremendously low frequency section transformer to be carried out the magnetic flux zeroing; This kind shunt circuit linearity insulating circuit apparatus has only very little amplitude response drift in the wide temperature range very much one.
Take technical scheme for achieving the above object
In this shunt circuit linearity insulating circuit apparatus, adopted subtraction formula frequency divider, input signal is resolved into low path and Gao Lu two parts.This subtraction formula frequency divider is made of a low-pass filter and a subtracter, and input signal is connected with the input end of low-pass filter and an input end of subtracter simultaneously, and the output terminal of low-pass filter is connected with another input end of subtracter.The output of low-pass filter is the signal of direct current tremendously low frequency section, low path signal just, and in the output signal of subtracter, the signal of direct current tremendously low frequency section is deducted, and remaining low frequency tremendously high frequency segment signal has so just obtained high road signal.Described subtraction formula frequency divider also can be made of a Hi-pass filter and a subtracter, and input signal is connected with the input end of Hi-pass filter and an input end of subtracter simultaneously, and the output terminal of Hi-pass filter is connected with another input end of subtracter.The output of Hi-pass filter is the signal of the paramount frequency range of low frequency, just high road signal, and in the output signal of subtracter, the signal of the paramount frequency range of low frequency is deducted, and remaining direct current tremendously low frequency segment signal has so just obtained the low path signal.
High road signal is connected to the elementary of a wide-band transformer, the low path signal is connected to the input end of linear photoconductor buffer circuit.With output signal addition after the amplitude match and regulate of the secondary signal and the photoelectric isolating circuit of wide-band transformer, the complete output signal after just having obtained isolating.Time constant by the capacitance-resistance loop in suitable setting or the adjustment photoelectric isolating circuit, the high frequency response of photoelectric isolating circuit is suitably promoted with respect to low frequency, the amplitude-frequency response that can compensate photoelectric isolating circuit and the low path that cause longer than time delay of transformer and crossover frequency place, high road caves in, and makes whole shunt circuit linearity insulating circuit obtain smooth amplitude-frequency response, linear phase-frequency response and accurate impulse response in broadband.
Remarkable result of the present invention
After by subtraction formula frequency divider input signal being resolved into Gao Lu and low path, if, can go back original input signal strictly according to the facts with the directly addition again of this two road signal.The phase-frequency response and the accurate impulse response that have smooth amplitude-frequency response, linearity between the output signal sum of subtraction formula frequency divider and the input signal.When the parameter of low-pass filter wherein (or Hi-pass filter) had error or parameter with temperature drift, above-mentioned characteristic still kept.This frequency divider need not to regulate stable performance.After Gao Lu and low path signal are isolated through transformer and photoelectricity respectively, if transformer and photoelectric isolating circuit have enough linearities, and overcome the delay-time difference between transformer and photoelectric isolating circuit, the signal sum after then isolating still has above-mentioned characteristic.Make it to need not other adjustings the coupling except that regulating, need not the transformer flux zeroing circuit the amplitude of high road after isolating and low path signal.By described subtraction formula frequency divider, overcome previously described first difficult point.
Time constant by the capacitance-resistance loop in reasonable setting or the adjustment photoelectric isolating circuit, the high frequency response of photoelectric isolating circuit suitably can be promoted with respect to low frequency, can compensate low path and amplitude-frequency response unevenness Gao Lu and signal that photoelectric isolating circuit causes than growing the time delay of transformer.The method need not to add delay circuit on high road, need not complicated adjusting, stable performance.By this method, overcome previously described second difficult point.
Description of drawings
Fig. 1 is a circuit diagram of the present invention, and a preferred isolated amplifier along separate routes is shown;
Fig. 2 is the low path, Gao Lu of subtraction formula frequency divider among Fig. 1 and the two and amplitude-frequency response signal;
Fig. 3 is the low path of subtraction formula frequency divider among Fig. 1 and the square-wave response waveform of Gao Lu;
Fig. 4 is the signal combination circuit input end among Fig. 1 and the waveform of output terminal;
Fig. 5 is the step response waveform of Fig. 1 circuit;
Fig. 6 is the 100kHz square-wave response waveform of photoelectric isolating circuit among Fig. 1;
Fig. 7 A, 7B and 7C be the resistance of time constant regulating circuit among Fig. 1 when different numerical value, the 10kHz square-wave response waveform of Fig. 1 circuit;
Fig. 8 is the another embodiment of the present invention circuit diagram, and the shunt isolated amplifier of a differential mode is shown.
Embodiment
As shown in Figure 1, each parts is formed by connecting by electronic devices and components in the frame of broken lines among the figure.Device of the present invention is shunt circuit linearity insulating circuit apparatus 200 (hereinafter to be referred as device 200) and is made up of low-pass filter 100 (hereinafter to be referred as wave filter 100), subtracter 101, transformer 26, linear photoconductor buffer circuit 102 (hereinafter to be referred as photoelectric coupled circuit 102), time constant regulating circuit 103 (hereinafter to be referred as circuit 103), low path gain adjusting circuit 104 (hereinafter to be referred as circuit 104) and signal combination circuit 105 (hereinafter to be referred as combiner 105).Measured signal 70 is connected to the input end 71 of device 200.The input end 71 of device 200 is connected to the input end 72 of wave filter 100 and the positive input terminal 74 of subtracter 101.The output terminal 73 of wave filter 100 both had been connected to the negative input end 75 of subtracter 101, was connected to the input end 77 of photoelectric coupled circuit 102 simultaneously again.Output terminal 78 connecting circuit 103 of photoelectric coupled circuit 102, the input end of output terminal 82 connecting circuit 104 of circuit 103, the output terminal 83 of circuit 104 connects the negative input end 79 of combiner 105.The output terminal of combiner 105 just installs 200 output terminal 81.The output terminal 76 of subtracter 101 connects the elementary of transformer 26, the positive input terminal 80 of the secondary connection combiner 105 of transformer 26.The terminal of the output terminal 76 of transformer 26 elementary connection subtracters 101 is an end of the same name with the secondary terminal that is connected combiner 105 positive input terminals 80.
Among Fig. 1, dielectric isolation layer 204 will install 200 and be separated into input side 202 and outgoing side 203.203 of input side 202 and outgoing sides insulate, and have only the less electric capacity of numerical value between the two.Input side has earth point 65, and outgoing side has earth point 66.Insulate between ground connection electricity 65 and the earth point 66, have only the less electric capacity of numerical value between the two.The circuit of the circuit of input side 202 and outgoing side 203 should be by the power supply power supply of mutual isolation.Dielectric isolation layer 204 can be formed by the electrical insulator of air-gap, vacuum layer or some other form.In the present embodiment, dielectric isolation layer 204 is made up of insulation course between the insulation of the insulation between transformer 26 windings, photoelectric coupled circuit 102 and input side, outgoing side power supply etc.
Transformer in transformer 26, photoelectric coupled circuit 102, the power supply and other stray capacitances lump together and cause about 50 picofarads of the total capacitance of striding separation layer 204, this capacitance size to be enough to make external vagabond current to reduce to minimum.
In the wave filter 100, input end 72 is connected with resistance 11, and resistance 11 is connected with resistance 12 and electric capacity 15, and resistance 12 is connected with electric capacity 16 and operational amplifier 19 positive input terminals again, electric capacity 15 is connected with operational amplifier 19 output terminals again, and electric capacity 16 is connected with earth point 65 again.The negative input end of operational amplifier 19 is connected to its output terminal.The output terminal of operational amplifier 19 is connected with resistance 13, resistance 13 is connected with resistance 14 and electric capacity 17, resistance 14 is connected with electric capacity 18 and operational amplifier 20 positive input terminals again, and electric capacity 17 is connected with operational amplifier 20 output terminals again, and electric capacity 18 is connected with earth point 65 again.The negative input end of operational amplifier 20 is connected to its output terminal.The output terminal of operational amplifier 20 is the output terminal 73 of wave filter 100 just.Low-pass filter 100 preferably adopts the Sallen-Key circuit topology, and approximate algorithm preferably quadravalence Bessel approaches, its-the 3dB cutoff frequency is preferably in 30kHz.The low-pass filter of other types, as the MFB topology, Butterworth approaches, and the cutoff frequency of other numerical value, also can to the numerical value between the 200kHz as 30kHz.Operational amplifier 19 and 20 is preferably selected the AD8039 of AnalogDevices for use.
In the subtracter 101, its positive input terminal 74 is connected with resistance 1, its negative input end 75 is connected with resistance 3, resistance 1 is connected with the positive input terminal of resistance 2 and operational amplifier 5 again, resistance 3 is connected with the negative input end of resistance 4 and operational amplifier 5 again, resistance 2 other ends connect earth point 65, and resistance 4 is connected with the output terminal of operational amplifier 5 again, and the output terminal of operational amplifier 5 is the output terminal 76 of subtracter 101 just.Subtracter 101 is actual to be a differential amplifier that enlargement factor is 1:1, at this as subtracter.Operational amplifier 5 is preferably selected the AD8055 of Analog Devices for use.
Input signal 70 obtains direct current and low-frequency component at low-pass filter 100 output terminals 73, just the low path signal through behind the low-pass filter 100.Input signal 70 and low path signal are sent to subtracter 101 again and do subtraction, in the signal of the output terminal 76 of subtracter 101, complete input signal 70 has been deducted its direct current and low-frequency component, only has been left the composition of low frequency tremendously high frequency, Here it is high road signal.Low path signal and Gao Lu signal two parts so just input signal 70 have been resolved into.When circuit delay enough in short-term, if in the signal of the output terminal 76 of subtracter 101, add the signal of low-pass filter 100 output terminals 73, just can recover input signal 70, do not have distortion.Also promptly through the low path and the high road signal of subtraction formula frequency divider gained, both sums can be gone back original input signal 70 strictly according to the facts, in other words, and this subtraction formula frequency divider, have smooth amplitude-frequency response and linear phase-frequency response between its low path and high road signal sum and the input signal 70, and accurate impulse response.This characteristic is not subjected to the influence of environment temperature, component parameter error substantially.
Among Fig. 2, curve 150 is amplitude-frequency responses of low-pass filter 100, also is low path signal amplitude-frequency response; Curve 151 be the signal of output terminal 76 of subtracter 101 with respect to the amplitude-frequency response of input signal 70, also be high road signal amplitude-frequency response; And curve 152 is low path and Gao Lu signal sum amplitude-frequency responses with respect to input signal 70.The frequency of the curve 150 the fastest place of roll-offing is-24dB/ octave, and the frequency of the curve 151 the fastest place of roll-offing is-6dB/ octave.The high road signal amplitude-frequency response of subtraction gained has a projection at crossover frequency place, at low-pass filter 100 be-when the 3dB cutoff frequency was the quadravalence Bessel wave filter of 30kHz, the peak value of projection appeared at the 35kHz place, and its value is 1.52 times of input signal.However, because low path signal and high road signal plus are vector additions, itself and signal curve 152 still approach straight line.
Among Fig. 3, waveform 153 is waveforms of input signal 70, is a 10kHz square wave, and waveform 154 is waveforms of the output terminal 73 of wave filter 100, and waveform 155 is waveforms of the output terminal 76 of subtracter 101.This figure has shown intuitively how subtraction formula frequency divider is separated into low path and Gao Lu two parts with a square-wave pulse.
In the photoelectric coupled circuit 102, at input side, its input end 77 is connected with the positive input terminal of operational amplifier 21, photodiode 62 in the negative input end of operational amplifier 21 and resistance 22, electric capacity 24 and the photoelectrical coupler 25 is connected, the output terminal of operational amplifier 21 is connected with resistance 23 and electric capacity 24, resistance 23 is connected with light emitting diode 64 in the photoelectrical coupler 25 again, and resistance 22 is connected with bias voltage-Vref1 again.At outgoing side, photodiode 63 in the negative input end of operational amplifier 28 and resistance 29, electric capacity 30 and the photoelectrical coupler 25 is connected, its positive input termination bias voltage+Vref2, its output terminal is connected with resistance 29, electric capacity 30, and the output terminal of operational amplifier 28 is the output terminal 78 of photoelectric coupled circuit 102 just.
Photoelectrical coupler 25 is the linear special-purpose optocouplers of isolating, and its inside is packaged with the photodiode 62 and 63 of a light emitting diode 64 and two couplings, and photodiode 62 is used for feedback, and photodiode 63 is used for the isolation coupling signal.This photoelectrical coupler is preferably selected the HCNR201 of Agilent for use.Bias voltage-Vref1 makes photoelectric coupled circuit 102 can transmit bipolar signal, if optocoupler selects HCNR201 for use, and resistance 22 is when getting 15k Ω ,-Vref1 is desirable-and 0.4V ,-Vref1 can be produced by voltage reference circuit.After-Vref1 determined, adjusting+Vref2 made that at input end 77 voltages be at 0 o'clock, and output terminal 78 voltages also are 0, and+Vref2 can be by producing behind the voltage reference circuit regulation voltage.Operational amplifier 21 and 28 is preferably selected the AD8038 of Analog Devices for use.Resistance 23 is 150 Ω.The selection of resistance 22 determines jointly that by the signal amplitude of input end 77 and the maximum photocurrent of photodiode 62 recommendation is 15k Ω.This moment, the recommendation of electric capacity 24 was 4.7pF.The value of resistance 29 equals the gain with photoelectric coupled circuit 102 expectations on duty of resistance 22, gets 0.5 in the gain of this photoelectric coupled circuit 102, so the value of resistance 29 is 7.5k Ω.Electric capacity 30 desirable 10pF.Under the said elements parameter, in the amplitude-frequency response of photoelectric coupled circuit 102, high frequency is raised with respect to low frequency.
In the circuit 104, the negative input end of operational amplifier 35 is connected with resistance 33, adjustable resistance 34, and adjustable resistance 34 is connected with the output terminal of operational amplifier 35 again.Its gain is about about 2 times.This partial circuit is the amplitude that is used for regulating the low path signal, makes it and high road Signal Matching.Operational amplifier 35 is preferably selected the AD8038 of Analog Devices for use.
Transformer 26 is wide-band transformers, its frequency of operation should satisfy can effectively pass through whole high roads signal, by Fig. 2 curve 151 as can be known its lowest operating frequency need extend to below the 1kHz, and its maximum operation frequency needs on the maximum operation frequency of whole shunt circuit linearity insulating circuit apparatus 200 expectations.And the dielectric voltage withstand between the primary and secondary of this transformer should satisfy the dielectric voltage withstand requirement of whole shunt circuit linearity insulating circuit apparatus 200 expectations.Electric capacity between primary and secondary should be as far as possible little, to reduce the ac leakage stream of 203 of device 200 input sides 202 and outgoing sides.In the present embodiment, transformer 26 has adopted line transformer to obtain frequency response preferably.Other forms of transformer is also available.This magnetic core of transformer preferably adopts China's A10-T12 * 6 * 4C toroidal core of peak electronics (Kunshan) company limited (ACME Electronics) more.Wire rod preferably adopts the three layer insulation wire of the TEX-E0.2mm of electrical industry Zhu Shi commercial firm of Furukawa Electronic.Do the twisted-pair feeder that twists into about every centimetre 1 with this wire rod, evenly flat around 22 circles on magnetic core, draw four wire heads and get final product.Can pass through 9kV withstand voltage test in a minute between primary and secondary.Its frequency of operation can be more than 100MHz.The about 25pF of electric capacity between primary and secondary.Resistance 27 is as terminal resistance, and when adopting above-mentioned transformer, its value is 136 Ω.
In the combiner 105, its positive input terminal 80 is connected with resistance 6, its negative input end 79 is connected with resistance 8, resistance 6 is connected with the positive input terminal of resistance 7 and operational amplifier 10 again, resistance 8 is connected with the negative input end of resistance 9 and operational amplifier 10 again, resistance 7 other ends connect earth point 66, and resistance 9 is connected with the output terminal of operational amplifier 10 again, and the output terminal of operational amplifier 10 just installs 200 output terminal 81.Combiner 105 is actual to be that an enlargement factor is 1: 1 a differential amplifier, is used for finishing the addition of low path signal and high road signal at this.The signal of the output terminal 78 of photoelectric coupled circuit 102 and the signal of input end 77 are anti-phase, so the signal of the signal of the output terminal 83 of circuit 104 and the input end 77 of photoelectric coupled circuit 102 also is anti-phase, be connected to the negative input end of combiner 105, just realized the addition of low path signal and high road signal.Operational amplifier 10 is preferably selected the AD8055 of Analog Devices for use.
The amplitude that the gain of regulating circuit 104 can change the low path signal makes it and high road Signal Matching, and regulating circuit 103 promotes suitably low path signal high frequency response, just can just install 200 output terminal 81 at the output terminal of combiner 105 and obtain signal with 70 one-tenth exact linear relationships of input signal.Provided the waveform of combiner 105 each points among Fig. 4.Waveform 156 is with the waveform after the signal inversion of combiner 105 negative input ends 79, and waveform 157 is waveforms of combiner 105 positive input terminals 80, and waveform 158 is waveforms of combiner output, also is the output waveform of device 200.Compare with the input waveform 153 among Fig. 3, visible output waveform 158 has been reduced input waveform 153 strictly according to the facts.Good square-wave response has illustrated that installing 200 has smooth amplitude-frequency response, linear phase-frequency response and accurate impulse response.Waveform among Fig. 5 is under the situation of about 1.5ns of rise time of input signal 70 itself, the square wave rising edge waveform that records at device 200 output terminal 81, the rise time of this waveform is about 3.5ns, this illustrated install 200 have above 100MHz-three dB bandwidth.
Obviously, the also fixedly gain of low path signal, and add gain adjusting circuit on high road, make it and the low path Signal Matching by the gain of regulating high road signal.
Circuit 103 is to be formed by connecting by adjustable resistance 31 and electric capacity 32.The purpose that adds circuit 103 is the time constant that will regulate photoelectric isolating circuit, make resistance 22 multiply by that electric capacity 24, resistance 29 multiply by electric capacity 30, resistance 31 multiply by electric capacity 32 these three product value sums (being called the photoelectric isolating circuit time constant) about about 220k Ω pF, and final purpose is that the high frequency response of photoelectric isolating circuit is suitably promoted with respect to low frequency, is used for compensating the amplitude-frequency response depression of photoelectric isolating circuit than the time delay of transformer long low path that causes and crossover frequency place, high road.The result who regulates will make photoelectric isolating circuit have square-wave response as Fig. 6 shape.The waveform of Fig. 6 is that input end 77 incoming frequencies in photoelectric coupled circuit 102 are after 100kHz, amplitude are the flat-top square wave of 360mV, and at the waveform that circuit 103 output terminals 82 obtain, visible square wave front edge has overshoot, and this is the result after high frequency is raised with respect to low frequency.By this method, just can compensate the crossover frequency place amplitude-frequency response depression that occurs than the long last high road that causes of transformer channels and low path signal sum because of time delay of photoelectric isolating circuit.Fig. 7 A, 7B and 7C have shown that at input signal 70 are frequencies when being the flat-top square wave of 10kHz, regulate resistance 31, when changing the photoelectric isolating circuit time constant, the square-wave response of device 200.Less than normal when resistance 31, the photoelectric isolating circuit time constant is less than normal, and high frequency is raised when too much, output waveform shown in Fig. 7 A, the wave top projection; Bigger than normal when resistance 31, the photoelectric isolating circuit time constant is bigger than normal, and when high boost was not enough, output waveform was shown in Fig. 7 B, and wave top is recessed; And when resistance 31 suitable, the photoelectric isolating circuit time constant is suitable, when high boost was suitable, output waveform was shown in Fig. 7 C, wave top is smooth.
By this method, low path that bring than transformer channels length the time delay that has overcome photoelectric isolating circuit effectively and Gao Lu with the uneven problem of signal frequency response, complicated compensating circuit and loaded down with trivial details adjustment have been removed from, also need not to add delay circuit, obtained good frequency response in transformer channels.
After other circuit element parameters are determined, required photoelectric isolating circuit time constant optimum value is also determined, so the value of resistance 31 is also determined, only need on first sample, to access the optimum value of resistance 31 in the actual production, subsequent product just can directly use the fixed resistance that optimum value is close therewith to replace resistance 31, need not each product is carried out the time constant adjustment, make production efficiency improve.
Circuit 103 also can be located at the input end 77 of photoelectric isolating circuit.
The adjusting of the adjusting of low path signal gain and photoelectric isolating circuit time constant also can realize by regulating resistance 22, resistance 29, electric capacity 24 and electric capacity 30.For example, can regulate the low path signal amplitude by the value of regulating resistance 22, resistance 29 and make it and high road Signal Matching, thereby the value of control capacittance 24, electric capacity 30 makes the suitable square-wave response that obtains shown in Fig. 7 C of photoelectric isolating circuit time constant again.Like this, circuit 103 and circuit 104 just can save.The shortcoming of this method is that the photoelectric isolating circuit time constant also can change when transferring gain.Another kind method is, gain adjusting circuit is located at Gao Lu, regulates resistance 22, resistance 29, electric capacity 24 and electric capacity 30 and reaches suitable photoelectric isolating circuit time constant, comes and the low path coupling by the amplitude of regulating high road signal again.
Circuit among Fig. 1 has very high common-mode rejection ratio to direct current and low frequency common mode interference, but smaller to the common mode inhibition of high frequency common-mode signals.For further improving the high frequency common mode rejection ratio of shunt circuit linearity insulating circuit apparatus, can make Fig. 1 circuit into difference form.Fig. 8 has provided the embodiment of difference form.In Fig. 8, low-pass filter 100, subtracter 101, transformer 26, photoelectric coupled circuit 102, time constant regulating circuit 103, low path gain adjusting circuit 104 and signal combination circuit 105 are the same with embodiment shown in Figure 1, are not giving unnecessary details at this.Different is, the driving of transformer and reception have made differential driving and differential received into, photoelectric isolating circuit has increased by a cover and photoelectric coupled circuit 102 duplicate circuit, it is photoelectric coupled circuit 108, also adopt differential driving and differential received, improve common-mode rejection ratio with this, especially the common-mode rejection ratio under the high frequency.
The low path signal of low-pass filter 100 output terminals 73, remove and deliver to subtracter 101, also deliver to single-ended to both-end change-over circuit 106, conversion of signals is become equal and opposite in direction, opposite polarity a pair of differential signal, then, the signal of positive polarity is wherein delivered to photoelectric coupled circuit 102, the signal of negative polarity is wherein delivered to photoelectric coupled circuit 108.At the output terminal of photoelectric coupled circuit, differential amplifier 110 converts this to single-ended signal to equal and opposite in direction, opposite polarity differential signal, delivers to circuit 103 then.
The high road signal of subtracter 101 output terminals 76 is to deliver to single-endedly to both-end change-over circuit 107 earlier, and conversion of signals is become equal and opposite in direction, opposite polarity a pair of differential signal, receives two elementary terminals of transformer 26 then respectively.Secondary two terminals of transformer have been received two input ends of differential amplifier 109 respectively, convert the differential signal of transformer output to single-ended signal, deliver to the positive input terminal of signal combiner 105 then.
Photoelectric coupled circuit 102 and 108 output terminal no longer need dc bias circuit.The dc offset voltage of photoelectric coupled circuit 102 and 108 output terminal has been cancelled out each other in differential amplifier 110, the output terminal of differential amplifier 110 does not have big dc offset voltage, has only the small direct current offset that causes because of circuit parameter is asymmetric, can fix earlier-Vref1, fine setting-Vref2 eliminates this direct current offset again.The photoelectric isolating circuit of difference form has also reduced direct current offset and temperature drift when improving common-mode rejection ratio.
Single-ended in both-end change-over circuit 106, the output terminal 73 of wave filter 100 is connected with the positive input terminal of operational amplifier 40 and resistance 43, the negative input end of operational amplifier 40 is connected with its output terminal, resistance 43 is connected with the negative input end and the resistance 42 of operational amplifier 41 again, resistance 42 is connected with the output terminal of operational amplifier 41 again, and the positive input terminal of operational amplifier 41 is connected with earth point 65.The output terminal of operational amplifier 40 is connected with the input end 77 of photoelectric coupled circuit 102; The output terminal of operational amplifier 41 is connected with the input end 84 of photoelectric coupled circuit 108.Operational amplifier 40,41 is preferably selected the AD8039 of Analog Devices for use.
Single-ended internal circuit to both-end change-over circuit 107 is with single-ended to arrive both-end change-over circuit 106 just the same.The output terminal 76 of subtracter 101 is connected with the positive input terminal of operational amplifier 36 and resistance 39.The output terminal of operational amplifier 36 and transformer 26 elementary terminals are connected, and the output terminal of operational amplifier 37 and transformer 26 another elementary terminals are connected.
Differential amplifier 109 can be identical with 110 with the internal circuit of subtracter 101, combiner 105.
The terminal terminal that connect operational amplifier 36 output terminals elementary with it that 26 levels of transformer connect the positive input terminal of differential amplifier 109 is end of the same name.
In photoelectric coupled circuit 108, resistance 46 can be adjustable, regulates the value of resistance 46, can make photoelectric coupled circuit 108 and photoelectric coupled circuit 102 couplings, improves the common-mode rejection ratio of entire circuit.Obviously, also can regulate resistance 23, make photoelectric coupled circuit 102 and photoelectric coupled circuit 108 couplings, improve the common-mode rejection ratio of entire circuit.
Those skilled in the art are when understanding, and some part of the present invention can have other embodiment.
Above-mentioned most preferred embodiment has been listed some preferred component type and numerical value, but obviously, can change, adds or remove some amplifiers, transformer, photoelectrical coupler, and about the element of model and numerical value, to adapt to the needs of various special-purposes.
Equally, the present invention described above implements with discrete elements, yet some of them amplifier, parts and subsystem also can be made assembly, hybrid circuit or the multi-chip module of integrated circuit.
In addition, though what describe in the most preferred embodiment is to regulate relevant element so that low path gain and high road coupling, suitable, the two-way photoelectric coupled circuit coupling of optocoupler channel time constant with manual mode, manually or automatic, analog or digital parameter regulation also can use among the present invention on any efficient circuit assembly.
Those skilled in the art understands, all can make various modifications for many details aspect of the above embodiment of the present invention, but this does not break away from design of the present invention.The present invention also can be used for relevant Signal Spacing aspect, and is not only on the electric signal measurement equipment.Therefore, scope of the present invention should have only appending claims to determine.
Claims (10)
1, a kind of shunt circuit linearity insulating circuit apparatus, with wideband input signal voltage after accurately amplifying, the broadband output signal voltage that Cheng Yuqi is linear, it comprises transformer circuit, photoelectric isolating circuit and signal combination circuit, it is characterized in that also containing following circuit:
(1) subtraction formula divider circuit resolves into direct current tremendously low frequency part and low frequency tremendously high frequency part two parts with described wideband input signal voltage;
(2) time constant regulating circuits (103), it is the time constant that to regulate photoelectric isolating circuit, the high frequency response of photoelectric isolating circuit is suitably promoted, to compensate photoelectric isolating circuit than the time delay of the transformer long low path that causes and the amplitude-frequency response unevenness at crossover frequency place, high road with respect to low frequency; Or only set the time constant of photoelectric isolating circuit by resistance G (22), resistance H (29), capacitor C (24) and the electric capacity D (30) of photoelectric isolating circuit inside.
2, by the described shunt circuit linearity insulating circuit apparatus of claim 1, it is characterized in that described subtraction formula divider circuit, constitute by a low-pass filter (100) and a subtracter (101), described wideband input signal voltage is connected with the input end of low-pass filter and an input end of subtracter simultaneously, and the output terminal of low-pass filter is connected with another input end of subtracter; Perhaps, described subtraction formula frequency divider, be made of a Hi-pass filter and a subtracter, described wideband input signal voltage is connected with the input end of Hi-pass filter and an input end of subtracter simultaneously, and the output terminal of Hi-pass filter is connected with another input end of subtracter.
3, by the described shunt circuit linearity insulating circuit apparatus of claim 2, it is characterized in that in the low-pass filter (100), input end (72) is connected with resistance E (11), resistance E (11) is connected with resistance F (12) and electric capacity A (15), resistance F (12) is connected with electric capacity B (16) and operational amplifier (19) positive input terminal again, electric capacity A (15) is connected with operational amplifier (19) output terminal again, and electric capacity B (16) is connected with earth point (65) again; Described low-pass filter adopts the Sallen-Key circuit topology, and approximate algorithm is that quadravalence Bessel approaches, its-the 3dB cutoff frequency at 30kHz between the 200kHz.
4, by the described shunt circuit linearity insulating circuit apparatus of claim 2, it is characterized in that in the subtracter (101), its positive input terminal (74) is connected with resistance A (1), its negative input end (75) is connected with resistance C (3), resistance A (1) is connected with the positive input terminal of resistance B (2) and operational amplifier (5) again, resistance C (3) is connected with the negative input end of resistance D (4) and operational amplifier (5) again, resistance B (2) other end connects earth point (65), resistance D (4) is connected with the output terminal of operational amplifier (5) again, and the output terminal of operational amplifier (5) is the output terminal (76) of subtracter (101) just.
5, by claim 1 or 2 or 3 described shunt circuit linearity insulating circuit apparatus, after it is characterized in that input signal (70) is through low-pass filter (100), obtain direct current and low-frequency component at low-pass filter (100) output terminal (73), input signal (70) and low path signal are sent to subtracter (101) again and do subtraction, in the signal of the output terminal (76) of subtracter (101), complete input signal (70) has been deducted its direct current and low-frequency component, only has been left the composition of low frequency tremendously high frequency; Described low path signal is the signal by the direct current tremendously low frequency section of low-pass filter output.
6, by the described shunt circuit linearity insulating circuit apparatus of claim 1, it is characterized in that time constant regulating circuit (103) is to be formed by connecting by adjustable resistance (31) and electric capacity E (32), this circuit is the time constant that will regulate photoelectric isolating circuit, make resistance G (22) multiply by capacitor C (24), resistance H (29) multiply by electric capacity D (30), resistance J (31) multiply by electric capacity E (32) these three product values with about 220kpF.
7, device as claimed in claim 1 is characterized in that, described photoelectric isolating circuit is the photoelectric isolating circuit by two difference form constituting of cover photoelectric isolating circuits.
8, device as claimed in claim 8, it is characterized in that, the photoelectric isolating circuit of the described difference form that constitutes of photoelectric isolating circuits by two covers, the current-limiting resistance of the light emitting diode of photoelectrical coupler that can be by regulating a cover photoelectric isolating circuit wherein, make it and another set of coupling, with the common-mode rejection ratio of photoelectric isolating circuit under high frequency that improves described difference form.
9, device as claimed in claim 1 is characterized in that, described transformer, and by the drives of difference output, its secondary signal is received by differential amplifier.
10, device as claimed in claim 1 is characterized in that, described transformer is a line transformer.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101547389A CN100514071C (en) | 2006-11-21 | 2006-11-21 | Shunt circuit linearity insulating circuit apparatus |
| PCT/CN2007/003266 WO2008061444A1 (en) | 2006-11-21 | 2007-11-19 | A split-path linear isolation circuit apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101547389A CN100514071C (en) | 2006-11-21 | 2006-11-21 | Shunt circuit linearity insulating circuit apparatus |
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| CN1963538A CN1963538A (en) | 2007-05-16 |
| CN100514071C true CN100514071C (en) | 2009-07-15 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB2006101547389A Expired - Fee Related CN100514071C (en) | 2006-11-21 | 2006-11-21 | Shunt circuit linearity insulating circuit apparatus |
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| CN (1) | CN100514071C (en) |
| WO (1) | WO2008061444A1 (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100514071C (en) * | 2006-11-21 | 2009-07-15 | 李君� | Shunt circuit linearity insulating circuit apparatus |
| FR2974909B1 (en) * | 2011-05-02 | 2013-05-31 | Chauvin Arnoux | GALVANIC INSULATION DEVICE |
| CN103353544B (en) * | 2012-06-15 | 2015-08-12 | 杭州祺来电子有限公司 | Shunt circuit linearity insulating circuit apparatus |
| CN102998502B (en) * | 2012-12-06 | 2015-03-04 | 陈实 | High-isolation voltage-resisting bidirectional signal sensor |
| CN103884894B (en) * | 2012-12-20 | 2018-07-13 | 北京普源精电科技有限公司 | A kind of improved shunt circuit linearity insulating circuit and its oscillograph |
| CN103884895B (en) * | 2012-12-20 | 2017-10-24 | 北京普源精电科技有限公司 | A kind of multi-channel linear isolation circuit and its oscillograph |
| CN103884888B (en) * | 2012-12-20 | 2018-03-16 | 北京普源精电科技有限公司 | Oscillograph with function of multimeter |
| CN103884893B (en) * | 2012-12-20 | 2017-10-24 | 北京普源精电科技有限公司 | A kind of shunt circuit linearity insulating circuit and its oscillograph |
| FR3009422A1 (en) * | 2013-07-31 | 2015-02-06 | Schneider Electric Ind Sas | CORRECTION OF THE BANDWIDTH OF A TRANSFORMER TO GAP |
| CN104135275A (en) * | 2014-07-17 | 2014-11-05 | 沈阳东软医疗系统有限公司 | A signal isolator and a method for debugging the signal isolator |
| CN104660193A (en) * | 2015-01-21 | 2015-05-27 | 上海新研工业设备有限公司 | Linear optocoupler transmitting analog signal circuit |
| CN105044422A (en) * | 2015-07-10 | 2015-11-11 | 深圳市航盛电子股份有限公司 | Liner signal high precision isolation circuit and linear signal high precision isolation circuit collection method |
| CN106373374A (en) * | 2016-11-28 | 2017-02-01 | 长沙广义变流技术有限公司 | Small signal isolation transmission circuit |
| CN110269634B (en) * | 2019-06-20 | 2023-09-12 | 上海联影医疗科技股份有限公司 | Isolation converter, X-ray generating device and medical imaging system |
| CN111579857A (en) * | 2020-04-21 | 2020-08-25 | 赵红雁 | Digital compensation type voltage sampling circuit and method for instrument |
| KR102475665B1 (en) * | 2020-11-12 | 2022-12-07 | 엑스멤스 랩스 인코포레이티드 | Crossover Circuit |
| CN113325265A (en) * | 2021-05-12 | 2021-08-31 | 武汉三相电力科技有限公司 | Device for detecting mixed traveling wave in power transmission line |
| CN117590056A (en) * | 2024-01-15 | 2024-02-23 | 广州德肯电子股份有限公司 | Alternating current-direct current signal isolation detection circuit and detection device |
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| JPH0272706A (en) * | 1988-09-07 | 1990-03-13 | Yokogawa Electric Corp | Insulating amplifier |
| JPH04129309A (en) * | 1990-09-19 | 1992-04-30 | Matsushita Electric Ind Co Ltd | Amplifier circuit |
| US5834973A (en) * | 1997-05-01 | 1998-11-10 | Fluke Corporation | Voltage isolation circuit for a measurement channel |
| CN100514071C (en) * | 2006-11-21 | 2009-07-15 | 李君� | Shunt circuit linearity insulating circuit apparatus |
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| WO2008061444A1 (en) | 2008-05-29 |
| CN1963538A (en) | 2007-05-16 |
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