WO1990014712A1 - Circuit de condensateur commute a faible courant - Google Patents

Circuit de condensateur commute a faible courant Download PDF

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Publication number
WO1990014712A1
WO1990014712A1 PCT/US1990/002244 US9002244W WO9014712A1 WO 1990014712 A1 WO1990014712 A1 WO 1990014712A1 US 9002244 W US9002244 W US 9002244W WO 9014712 A1 WO9014712 A1 WO 9014712A1
Authority
WO
WIPO (PCT)
Prior art keywords
switched capacitor
capacitor circuit
current
circuit
variable bias
Prior art date
Application number
PCT/US1990/002244
Other languages
English (en)
Inventor
King Fu Lee
Original Assignee
Motorola, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Motorola, Inc. filed Critical Motorola, Inc.
Priority to PCT/US1990/005182 priority Critical patent/WO1991016764A1/fr
Publication of WO1990014712A1 publication Critical patent/WO1990014712A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H19/00—Networks using time-varying elements, e.g. N-path filters
    • H03H19/004—Switched capacitor networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0211—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the supply voltage or current
    • H03F1/0216—Continuous control

Definitions

  • This invention relates generally to energy (battery) saving circuits, and more particularly to the battery saving of a switched capacitor circuit that may be used as a switched capacitor filter.
  • Switched capacitor circuits are known. Such circuits are the product of circuit design techniques commonly used to miniaturize (integrate) components. In portable (hand-held) communication applications, components such as filters are often reduced to integrated circuit (IC) form.
  • IC integrated circuit
  • a switched capacitor circuit utilizes the fact that when a capacitor is switched between a signal to be sampled and ground at a rate many times that of the frequency of the sampled signal, the capacitor will simulate the circuit behavior of a resistor.
  • a switched capacitor circuit having reduced energy consumption.
  • a variable bias supplies an operating current to the switched capacitor circuit.
  • the variable bias supplies a lower, but non-zero, current.
  • FIG. 1 is a schematic diagram of a switched capacitor circuit according to the present invention.
  • a switched capacitor low-pass filter according to the present invention is shown.
  • a conventional switched capacitor filter 10 comprises an operational amplifier 16 and a pair of capacitors 12 and 14 (that simulate resistors when switched rapidly) forming a simple low-pass filter configuration.
  • An input signal, Vjn is coupled to an inverting input of the operational amplifier (Op Amp) 16 by a pair of sampling switches 18.
  • Op Amp operational amplifier
  • the switch 18 When the switch 18 is closed for the EVEN phase, the current provided by V
  • the voltage VIN developed across the capacitor 12 is fed to the Op Amp 16 when the switch 18 is closed for the ODD phase.
  • the positive input of the Op Amp 16 As in a conventional active RC low-pass filter, the positive input of the Op Amp 16 is grounded.
  • the Op Amp 16 provides an output signal, Vout. ⁇ portion of which is fed back to the negative input of the Op Amp 16 by a capacitor 22 and the capacitor 14 (in conjunction with the sampling switches 18).
  • a bias network 30 supplies a bias output 32 to the operational amplifier 16.
  • a resistor 34 and an N-channel MOSFET 36 set up a current reference 11 that is mirrored by a pair of N-channel MOSFETs 38 and 42 as currents 12 and 13 respectively.
  • a P-channel MOSFET 44 provides the current source capability for the mirrored currents I 2 and 1 3.
  • a control signal is coupled to the gate of an N channel MOSFET 46 to selectively turn the current 12 ON and OFF.
  • the control signal will be HIGH, which turns on the MOSFET 46. In this way, the sum of currents 12 and 13 will bias the Op Amp 16 at a current having full drive capability.
  • the control line is LOW, the MOSFET 46 becomes non-conductive and no current will flow through it.
  • the duty cycle (or duration) the control signal will remain LOW is selectable to obtain the current reduction desired. The longer the control signal is LOW, the less current is consumed.
  • This lower current mode has limited drive capability, but the current 13 from the MOSFET 42 will bias the Op Amp 16 in a standby mode. Although limited, this current is sufficient to compensate for any leakage in the Op Amp16 and to eliminate the DC transients from occurring when reactivated. During the standby mode, the limited current 13 is insufficient to provide for the switching of the capacitors 12 and 14. Therefore, the switching signals (ODD and EVEN) are also disabled. To disable the switching signals, the LOW control signal is ANDed (52) with the CLOCK signal 50 to prevent the clock signal from driving the phase generation circuit 20.

Abstract

Le circuit de condensateur commuté (10) se caractérise par une consommation d'énergie réduite. Une polarisation variable (30) fournit un courant opérationnel (32) au circuit de condensateur commuté (10). En période de non-utilisation du circuit (10), la polarisation variable (30) fournit un courant inférieur mais non homopolaire.
PCT/US1990/002244 1989-05-24 1990-04-26 Circuit de condensateur commute a faible courant WO1990014712A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1990/005182 WO1991016764A1 (fr) 1990-04-26 1990-09-13 Circuit de condensateur commute a faible consommation de courant

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US35605089A 1989-05-24 1989-05-24
US356,050 1989-05-24

Publications (1)

Publication Number Publication Date
WO1990014712A1 true WO1990014712A1 (fr) 1990-11-29

Family

ID=23399898

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1990/002244 WO1990014712A1 (fr) 1989-05-24 1990-04-26 Circuit de condensateur commute a faible courant

Country Status (1)

Country Link
WO (1) WO1990014712A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5155394A (en) * 1991-02-12 1992-10-13 National Semiconductor Corporation Bias distribution circuit and method using FET and bipolar
US5543745A (en) * 1994-06-03 1996-08-06 Mitsubishi Denki Kabushiki Kaisha Voltage controlled current source and bias generation circuit using such current source
CN1035712C (zh) * 1991-09-18 1997-08-20 Eev有限公司 感性输出电子管放大器
US6255885B1 (en) 1997-12-22 2001-07-03 Per-Olof Brandt Low voltage transistor biasing

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4521743A (en) * 1983-12-29 1985-06-04 Cordis Corporation Switched capacitor amplifier
US4760346A (en) * 1986-09-30 1988-07-26 Motorola, Inc. Switched capacitor summing amplifier

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4521743A (en) * 1983-12-29 1985-06-04 Cordis Corporation Switched capacitor amplifier
US4760346A (en) * 1986-09-30 1988-07-26 Motorola, Inc. Switched capacitor summing amplifier

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5155394A (en) * 1991-02-12 1992-10-13 National Semiconductor Corporation Bias distribution circuit and method using FET and bipolar
CN1035712C (zh) * 1991-09-18 1997-08-20 Eev有限公司 感性输出电子管放大器
US5543745A (en) * 1994-06-03 1996-08-06 Mitsubishi Denki Kabushiki Kaisha Voltage controlled current source and bias generation circuit using such current source
US6255885B1 (en) 1997-12-22 2001-07-03 Per-Olof Brandt Low voltage transistor biasing

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