CA2435310C - High efficiency wideband linear wireless power amplifier - Google Patents

High efficiency wideband linear wireless power amplifier Download PDF

Info

Publication number
CA2435310C
CA2435310C CA2435310A CA2435310A CA2435310C CA 2435310 C CA2435310 C CA 2435310C CA 2435310 A CA2435310 A CA 2435310A CA 2435310 A CA2435310 A CA 2435310A CA 2435310 C CA2435310 C CA 2435310C
Authority
CA
Canada
Prior art keywords
input signal
supply voltage
envelope detector
voltage
power amplifier
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Fee Related
Application number
CA2435310A
Other languages
French (fr)
Other versions
CA2435310A1 (en
Inventor
James E. Mitzlaff
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Google Technology Holdings LLC
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
Publication of CA2435310A1 publication Critical patent/CA2435310A1/en
Application granted granted Critical
Publication of CA2435310C publication Critical patent/CA2435310C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/005Control of transmission; Equalising
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03FAMPLIFIERS
    • H03F1/00Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0211Modifications 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
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03FAMPLIFIERS
    • H03F1/00Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0211Modifications 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
    • H03F1/0244Stepped control
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03FAMPLIFIERS
    • H03F1/00Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32Modifications of amplifiers to reduce non-linear distortion

Abstract

An apparatus (150), system (100) and method (400-440) are illustrated for power amplification of an input signal to produce a substantially linear amplified output signal, for broadband wireless applications such as 3G cellular and broadband CDMA systems, without causing significant intermodulation distortion or spectral growth. The preferred system (100) embodiment includes an envelope detector (110) to determine an envelope detector voltage from the input signal; a tracking power supply (120) to determine a supply voltage, preferably as a substantially quantized replica of the envelope detector voltage; an input signal conditioner (150) to determine, in response to the supply voltage, a corresponding phase adjustment and a corresponding gain adjustment, and to modify the input signal using the corresponding phase adjustment and the corresponding gain adjustment to produce a conditioned input signal for power amplification. The preferred system (100) embodiment further includes a power amplifier which operates using the supply voltage, and which amplifies the conditioned input signal to produce the amplified output signal. In the preferred embodiment, the corresponding phase adjustment and a corresponding gain adjustment are separately and independently determined from piecewise linear mappings of a phase response and an amplitude response, respectively, of the power amplifier to a range of variation of the supply voltage.

Description

HIGH EFFICIENCY WIDEBAND LINEAR
WIRELESS POWER AMPLIFIER
Field of the Invention The present invention relates, in general, to power amplifiers and, more particularly, to an apparatus, method and system for high efficiency, wideband linear power amplification in wireless applications, such as broadband CDMA
and 3G
cellular systems.
Background of the Invention Power amplifiers for wireless transmission applications, such as radio frequency ("RF") power amplifiers, are utilized in a wide variety of communications and other electronic applications. Ideally, the input-output transfer function of a power amplifier should be linear, with a perfect replica of the input signal, increased in amplitude, appearing at the output of the power amplifier.
In addition, for greater efficiency, various RF systems, such as cellular systems, attempt to run power amplifiers at or near their saturation levels, in which the actual output power of the amplifier is just below its maximum rated power output level. This power output level is generally related to the supply voltage (or supply power) to the power amplifier, such that a greater supply voltage will produce a correspondingly greater output power from the amplifier; for higher power input signals, a correspondingly greater actual power output is required to maintain the amplifier at or near saturation. In various prior art amplifiers, however, the supply voltage to the power amplifier is fixed. Given a typical usage situation in which actual power output from the amplifier may vary by a range of several orders of magnitude, use of a fixed supply voltage is highly inefficient, as output power is often an order of magnitude below its maximum, and the power amplifier is not maintained at or near its saturation levels.
Various techniques have evolved to vary the supply voltage to maintain the power amplifier at or near saturation. One such technique is power supply modulation ("PSM") which varies, or modulates, the supply voltage to the power amplifier, in order to maintain the power amplifier at or near saturation while
2 the input signal varies over time. For PSM, the supply voltage of the amplifier tracks the input signal variations, typically utilizing a signal detector in conjunction with a tracking power supply. In the prior art, however, the various PSM techniques have generally been limited to narrowband applications, or have poor efficiency characteristics.
For example, one prior art PSM technique, known as Envelope Elimination Restoration ("EER"), utilizes a limiter to provide an essentially constant drive level to the power amplifier to maintain the amplifier in a hard saturation state and increase efficiency. Use of the limiter, however, greatly expands the bandwidth of the RF signal input to the amplifier, and requires very accurate tracking of the input signal envelope, with a power supply switching frequency approximately ten times greater than the bandwidth of the RF input signal. As these switching frequencies increase, the transistors within the tracking power supply become less efficient, resulting in excessive power losses. The resulting bandwidth expansion of the limiter also requires the bandwidth capability of the amplifier to be significantly greater than the input signal bandwidth, limiting the EER configuration to narrow bandwidth applications, such as amplitude modulation ("AM") RF broadcasts.
Another prior art PSM technique, known as Envelope Tracking ("ET"), does not utilize the limiter of EER, and consequently may be suitable for higher bandwidth applications. Use of envelope tracking, however, introduces significant non-linearities in the output signal of the power amplifier, such as gain distortions, phase distortions, and other voltage parasitics. More particularly, while power amplifiers comprised of LDMOS (laterally diffused MOSFET) circuitry have good linearity with respect to input power, such LDMOS and other types of power amplifiers have large variations in gain and phase as a function of supply voltage.
When PSM techniques are utilized for amplification efficiency, these non-linearities cause intermodulation distortion ("IMD") in multicarrier frequency division multiple access ("FDMA") or time division multiple access ("TDMA") systems; and spectral growth in code division multiple access ("CDMA") systems. These various distortions also degrade output signal quality and may have other detrimental effects, such as decreased data throughput.
3 As a consequence, a need remains for an apparatus, method and system to provide high efficiency power amplification in broadband (or wideband) applications, such as 3G and other wideband cellular or RF applications. Such an apparatus, method and system should provide linear power amplification, minimizing any phase, gain, and other distortions. In addition, such an apparatus, method and system should be cost-effective and capable of implementation in existing RF
transmission systems, such as existing cellular base stations.
Summary of the Invention An apparatus, method and system are provided for power amplification of an input signal to produce a substantially linear amplified output signal, for broadband wireless applications such as 3G cellular and broadband CDMA
systems, without creating significant intermodulation distortion or spectral growth.
The preferred system 100 embodiment includes an envelope detector 1 S 110, a tracking power supply 120, an input signal conditioner 150, and a power amplifier 170. The envelope detector 110 is utilized to determine an envelope detector voltage from the input signal, and the tracking power supply 120 is utilized to determine a supply voltage from the envelope detector voltage, preferably as a substantially quantized version of the envelope detector voltage. The supply voltage is utilized to maintain the power amplifier 170 at or near its saturation level. An input signal conditioner 150 is utilized to predistort or condition the input signal, to form a conditioned input signal, such that when the conditioned input signal is amplified by the power amplifier 170 using the supply voltage, the amplified output signal is a substantially linear, amplified replica of the input signal.
In response to the supply voltage, the input signal conditioner 150 determines a corresponding phase adjustment and a corresponding gain adjustment.
In the preferred embodiment, the corresponding phase adjustment is selected from a plurality of predetermined phase adjustments in response to the supply voltage, and the corresponding gain adjustment is selected from a plurality of predetermined gain adjustments, also in response to the supply voltage. The plurality of predetermined phase adjustments and the plurality of predetermined gain adjustments are determined separately and independently, preferably from respective piecewise linear mappings
4 of a phase response and a gain response of the power amplifier to a range of variation of the supply voltage. The input signal conditioner then modifies the input signal using the corresponding phase adjustment and the corresponding gain adjustment to produce the conditioned input signal.
S The preferred system 100 embodiment also includes a first delay circuit 160, to synchronize the input signal with the supply voltage, and a second delay circuit 165 to synchronize the supply voltage with the conditioned input signal.
The apparatus, method and system embodiments of the present invention provide for high efficiency power amplification in broadband (or wideband) applications, such as 3G and other wideband cellular or RF applications, without significant bandwidth limitations, without intemodulation distortion, and without spectral growth. The various embodiments of the present invention effectively provide linear power amplification, minimizing any phase, gain, and other distortions.
In addition, the apparatus, method and system of the present invention are cost-effective and capable of implementation in existing RF transmission systems, such as existing cellular base stations.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.
Brief Description of the Drawings Figure 1 is a block diagram illustrating apparatus and system embodiments to provide for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention.
Figure 2 is a graphical diagram illustrating an exemplary input signal voltage, an exemplary envelope detector voltage, and an exemplary tracking power supply voltage,, for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention.
Figure 3 is a graphical diagram illustrating an exemplary nonlinear phase variation, an exemplary piecewise linear mapping to the nonlinear phase variation, and an exemplary piecewise linear mapping for phase adjustments for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention.
Figure 4 is a graphical diagram illustrating an exemplary nonlinear gain adjustment, an exemplary piecewise linear mapping to the nonlinear gain
5 variation, and an exemplary piecewise linear mapping for gain adjustments for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention.
Figure 5 is a flow diagram illustrating a method embodiment to provide for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention.
Detailed Description of the Invention While the present invention is susceptible of embodiment in many different forms, there are shown in the drawings and will be described herein in detail specific embodiments thereof, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated.
As mentioned above, a need remains for accurate, linear high efficiency power amplification for broadband or wideband applications. The apparatus, method and system embodiments of the present invention provide for such high efficiency power amplification in broadband (or wideband) applications, such as 3G and other wideband cellular or RF applications, without significant bandwidth limitations, without intemodulation distortion, and without spectral growth.
The various embodiments of the present invention effectively provide linear power amplification, minimizing any phase, gain, and other distortions. In addition, the apparatus, method and system of the present invention are cost-effective and capable of implementation in existing RF transmission systems, such as existing cellular base stations.
Figure 1 is a block diagram illustrating apparatus 150 and system 100 embodiments to provide for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention. The system 100 is
6 preferably included within a base station or other transceiver for wireless communication, such as for 3G cellular systems, wideband CDMA, or other cellular, PCS or RF communication systems. The system 100 includes an input signal conditioner apparatus 150, an envelope detector 110, a tracking power supply 120, and a power amplifier ("PA") 170. The power amplifier 170 is preferably coupled to an antenna (or antenna array) 175 for wireless transmission of an amplified, output signal on line 171. As discussed in greater detail below, to provide more accurate synchronization of the supply voltage to the power amplifier 170 (on line 122) with a conditioned input signal, the system 100 also preferably includes first and second delay circuits 160 and 165, respectively.
Continuing to refer to Figure l, the envelope detector 110 and tracking power supply 120 are utilized to track the input signal (on line 101) and provide a variable supply voltage (on line 122) to the power amplifier 170, to maintain the power amplifier 170 at or near saturation~and increase the efficiency of the power amplifier over a wide range of variation of the input signal. The input signal conditioner apparatus 150, in accordance with the present invention, includes a nonlinear phase mapper 125, a phase adjuster 130, a nonlinear gain mapper 135, and a gain adjuster 140. As discussed in greater detail below, the input signal conditioner apparatus 150 will essentially predistort (or condition) an input signal (on line 161) (which has been delayed (by first delay circuit 160)), to provide a conditioned input signal to the power amplifier 170 (on line 151), to counteract any phase and gain distortions introduced within the power amplifier 170 from variations in the supply voltage (on lines 121 and 122) provided by the tracking power supply 120. As a consequence, the use of the input signal conditioner apparatus 150, in conjunction with the use of the envelope detector 110 and tracking power supply 120 to vary the supply voltage to the power amplifier 170, minimizes phase and gain distortions in the amplified output signal, and provides for effectively linear, high efficiency power amplification in broadband applications.
Figure 2 is a graphical diagram illustrating an exemplary input signal voltage (205), an exemplary envelope detector voltage (210), and an exemplary tracking power supply voltage (220), for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention.
7 Refernng to both Figures 1 and 2, the envelope detector 110 tracks or detects the "envelope" of an input signal (on line 101), such as envelope detecting the exemplary input signal voltage 205, to produce an envelope detector voltage or signal (output on line 111), such as exemplary envelope detector voltage 210. A tracking power supply 120 is then utilized to further track (or quantize) the envelope detector voltage (e.g., envelope detector voltage 210), and provide a higher or greater level of supply voltage and current to the power amplifier 170, in comparison to a level typically available directly from an envelope detector 110. In the preferred embodiment, for faster operation and for greater bandwidth capability (e.g., to 10 MHz or more), the tracking power supply 120 is stepped or switched, providing a quantized power supply voltage or signal (on line 121 and, following second delay circuit 165, on line 122) to power amplifier 170, such as exemplary power supply voltage 220. As illustrated in Figure 2, the exemplary power supply voltage 220 output from the tracking power supply 120 is approximately a stepped or quantized version or replica of the exemplary envelope detector voltage 210, and may also include various ringing, overshoot, and other voltage distortions, as illustrated by distortions 221 and 222, for example. By tracking the input signal (on line 101), the envelope detector 110 and tracking power supply 120 provide a variable supply voltage to the power amplifier 170 (on line 122), and enable the power arriplifier 170 to be maintained at or near saturation over a wide range of magnitudes of the input signal, to provide for highly efficient amplification of the input signal.
As mentioned above, however, such envelope tracking by the envelope detector 110 and tracking power supply 120, to provide a variable supply voltage to the power amplifier 170, typically introduces significant non-linearities in the output signal (on line 171) of the power amplifier 170, such as gain distortions, phase distortions, and other parasitics. More particularly, variations in gain and phase in the output signal (on line 171) of the power amplifier 170 are correlated to or otherwise occur as a function of the supply voltage (on line 122). These variations in gain and phase of the output signal of the power amplifier 170, as a function of supply voltage, may be calibrated or otherwise empirically determined, preferably during the initial design or manufacture of the power amplifier 170, and may be utilized to create the nonlinear phase and gain mappings (illustrated in Figure 3 and 4, for example)
8 respectively implemented in nonlinear phase mapper 12S and nonlinear gain mapper 135.
Figure 3 is a graphical diagram illustrating an exemplary nonlinear phase variation (30S), an exemplary piecewise linear mapping to the nonlinear phase S variation (dashed lines 310, 31 S and 320), and an exemplary piecewise linear mapping for phase adjustments (lines 309, 314 and 319), with respect to supply voltage, for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention. As mentioned above, the phase of the amplified output signal from the power amplifier 170 (on line 171), in comparison to the input signal (on line 101), generally varies as a nonlinear function of the supply voltage to the power amplifier (on line 122), and may be calibrated or otherwise determined, to provide, for example, exemplary nonlinear phase variation 305. In the preferred embodiment, a piecewise linear approximation is made to the determined nonlinear phase variation, resulting in, for example, an exemplary 1S piecewise linear mapping to the nonlinear phase variation (dashed lines 310, 31S and 320). To predistort the input signal to accommodate this phase variation, a distortion opposite to the piecewise linear mapping to the nonlinear phase variation is utilized, resulting in an exemplary piecewise linear mapping for phase adjustments (illustrated as solid lines 309, 314 and 319 in Figure 3). In the preferred embodiment, a plurality of corresponding phase adjustments are stored in the non-linear phase mapper 12S as a predetermined set of coefficients corresponding to particular supply voltages. As a consequence, for any given supply voltage (or range of supply voltages) to the power amplifier 170, such as supply voltage level 321, a corresponding phase adjustment may be determined by the nonlinear phase mapper 125, such as phase adjustment 322.
2S This phase adjustment, determined by the nonlinear phase mapper 125, will be utilized by the phase adjuster 130 (in the input signal conditioner 1 SO) to predistort or condition the phase of the input signal, to form an intermediate conditioned input signal (on line 131 of Figure 1); this intermediate conditioned input signal is then gain conditioned (below), to thereby create a conditioned input signal, (i.e., the input signal having been predistorted for both phase and gain variations), which when amplified using the supply voltage provided by the tracking power supply 120, will provide an
9 PCT/USO1/49343 output signal which is generally or approximately an amplified, linear replica of the input signal.
Figure 4 is a graphical diagram illustrating an exemplary nonlinear gain (or amplitude) variation (325), an exemplary piecewise linear mapping to the nonlinear gain variation (dashed lines 330, 335 and 340), and an exemplary piecewise linear mapping for gain adjustments (lines 329, 334 and 339), with respect to supply voltage, for high efficiency, wideband linear power amplification in wireless applications in accordance with the present invention. As mentioned above, the gain of the amplified output signal from the power amplifier 170 (on line 171), in comparison to the input signal (on line 101), generally varies as a nonlinear function of the supply voltage to the power amplifier (on line 122), and may be calibrated or otherwise determined, to provide, for example, exemplary nonlinear gain variation 325. In the preferred embodiment, a piecewise linear approximation is also made to the determined nonlinear gain variation, resulting in, for example, an exemplary piecewise linear mapping to the nonlinear gain variation (dashed lines 330, 335 and 340). To predistort the input signal to accommodate this gain variation, a distortion opposite to the piecewise linear mapping to the nonlinear gain variation is utilized, resulting in an exemplary piecewise linear mapping for gain adjustments (illustrated as solid lines 329, 334 and 339 in Figure 4). In the preferred embodiment, a plurality of corresponding gain adjustments are stored in the non-linear gain mapper 135 as a predetermined set of coefficients corresponding to particular supply voltages.
As a consequence, for any given supply voltage (or range of supply voltages) to the power amplifier 170, such as supply voltage level 321, a corresponding gain adjustment may be determined by the nonlinear gain mapper 135, such as gain adjustment 323.
This gain adjustment, determined by the nonlinear gain mapper 135, will be utilized by the gain adjuster 140 (in the input signal conditioner 150) to predistort or condition the gain of the intermediate conditioned input signal (i.e., the input signal following its phase adjustment on line 131 (above)), to thereby create the conditioned input signal.
The conditioned input signal, which effectively is the input signal having been predistorted for both phase and gain variations, when amplified using the supply voltage provided by the tracking power supply 120, will provide an output signal which is generally or approximately an amplified, linear replica of the input signal.

It should be noted that the nonlinear phase and gain adjustments, and their piecewise linear approximations, will generally be different from each other (e.g., a nonlinear gain variation, such as exemplary nonlinear gain variation 325, will have a different calibration (graph or curve), and different piecewise linear 5 approximations, than a nonlinear phase variation, such as exemplary nonlinear phase variation 305). As a consequence, in the preferred embodiment, the respective plurality of nonlinear phase adjustments and plurality of nonlinear gain adjustments, as functions of supply voltage, are each calibrated or otherwise determined separately and independently. It should also be noted that the phase and gain adjustments may
10 occur in any order, in addition to that illustrated in Figure 1, such as a gain adjustment to create an intermediate conditioned input signal followed by a phase adjustment, or a gain adjustment occurnng concurrently with a phase adjustment.
Refernng again to Figure l, for any given input signal at any given time, the envelope detector 110 tracks or detects the "envelope" of the input signal (on line 101), to produce an envelope detector voltage (output on line 111). The tracking power supply 120 is then utilized to further track (or quantize) the envelope detector' voltage, and provide a higher or greater level of supply voltage and current to the power amplifier 170. In the preferred embodiment, the tracking power supply 120 is stepped or switched, providing a quantized power supply voltage (on line 121 and, following second delay circuit 165, on line 122) to power amplifier 170. In the preferred embodiment, three steps or quantizations are utilized, as any increased efficiency available from additional steps would generally be lost from an increase in complexity of the tracking power supply 120. To accommodate any delay incurred during such tracking by the envelope detector 110 and tracking power supply 120, first delay circuit 160 is utilized to delay and thereby synchronize the input signal (on line 161) with a corresponding supply voltage on line 121.
The supply voltage on line 121 is input into both the nonlinear phase mapper 125 and nonlinear gain mapper 135. As indicated above, for any given value of the supply voltage (on line 121), the nonlinear phase mapper 125 and nonlinear gain mapper 135 provide a corresponding phase adjustment and a corresponding gain adjustment, respectively. Utilizing the corresponding phase adjustment and the corresponding gain adjustment, respectively, the phase adjuster 130 and the gain
11 adjuster 140 modify the (delayed) input signal (on line 161), to provide a predistorted or conditioned input signal (on line 151) to the power amplifier 170. As mentioned above, such gain and phase conditioning may occur in any order, and if occurring sequentially, there will be an intermediate conditioned signal, e.g., an intermediate phase conditioned input signal followed by the gain conditioning to create the conditioned input signal, or an intermediate gain conditioned input signal followed by the phase conditioning to create the conditioned input signal.
To accommodate any delay incurred during such phase and gain determinations and adjustments by the input signal conditioner 150, a second delay circuit 165 is utilized to delay and thereby synchronize the supply voltage (on line 122) with the corresponding conditioned input signal (on line 151). The supply voltage to the power amplifier 170 (on line 122) will then be the same value as the supply voltage (on line 121 ) previously provided as inputs to the nonlinear phase and gain mappers 125 and 135 and utilized to determine the phase and gain adjustments to predistort the input signal to produce the conditioned input signal. As a consequence, the amplification of the conditioned input signal by the power amplifier 170, utilizing the synchronized supply voltage on line 122, will produce a generally linear, amplified replica, without phase or gain distortions, of the input signal, on line 171.
The amplified signal may then be utilized, for example, for broadcast via antenna 175.
In addition, utilizing the variable supply voltage, determined at any instant of time by the corresponding tracking of the input signal, allows the maximum output power of the power amplifier 170 to be varied accordingly, thereby allowing the power amplifier to be maintained at or near saturation over a wide range of input signal power levels.
A particularly significant and novel feature of the present invention is the input of the supply voltage, on line 121, from the tracking power supply 120, into the input signal conditioner 150, rather than input of the envelope detector voltage (on line 111) from the envelope detector 110. As a consequence, the input signal conditioner 150 may also provide phase and gain adjustments, in the conditioned input signal, to additionally accommodate overshoot, ringing and other nonlinear distortions, such as distortions 221 and 222 illustrated in Figure 2, which would otherwise detrimentally affect the linearity characteristics of the amplified output
12 signal. In addition, this use of a quantized tracking power supply 120 avoids the bandwidth limitations of a continuously tracking power supply, and allows use of the system 100 for wideband applications, such as a 10 MHz or greater bandwidth.
Figure 5 is a flow diagram illustrating a method embodiment to provide for high efficiency, wideband linear power amplification in wireless applications, and provides a useful summary of the present invention. In the preferred embodiment, each step of the method (other than start step 400 and return step 440) runs or occurs essentially continuously, for as long as an input signal is to be amplified, as may be illustrated by the ongoing or continuous operation of the system I O I00 circuitry of Figure 1. Referring to Figure 5, the method begins, start step 400, with envelope tracking an input signal to produce an envelope detector voltage (or signal), step 405, preferably by envelope detector 110. Next, in step 410, the envelope detector voltage is quantized to produce a supply voltage (or signal), preferably by the tracking power supply 120. From the supply voltage, a corresponding phase adjustment and a corresponding gain adjustment are determined, step 415, preferably by the respective nonlinear phase mapper 125 and the nonlinear gain mapper 135. As mentioned above, in the preferred embodiment, for an entire range of potential supply voltages, a plurality of corresponding phase adjustments and a plurality of corresponding gain adjustments are calibrated or otherwise determined, and preferably stored as corresponding coefficients in the nonlinear phase mapper 125 and the nonlinear gain mapper 135, respectively.
Continuing to refer to Figure 5, the input signal is synchronized with the supply voltage, step 420, preferably by first delay circuit 160. Next, the synchronized (or delayed) input signal is modified using the corresponding phase adjustment and the corresponding gain adjustment, to produce a conditioned input signal, step 425, preferably by the phase adjuster 130 and the gain adjuster 140, respectively. For example, in the preferred embodiment, the phase adjuster 130 and the gain adjuster 140 may be irr~plemented as multipliers, to multiply the input signal respectively by corresponding phase adjustment coefficients and corresponding gain adjustment coefficients, to produce the conditioned input signal on line 151.
The supply voltage, for the power amplifier 170, is synchronized with the conditioned input signal, step 430, preferably by the second delay circuit 165. Using the
13 synchronized supply voltage, the conditioned input signal is amplified, such as by power amplifier 170, to produce an output signal for transmission on line 171, step 435. The method may end, return step 440, when there is no longer any input signal requiring amplification but, as mentioned above, in the preferred embodiment, each step of the method (other than start step 400 and return step 440) runs or occurs effectively continuously.
As may be apparent from the discussion above, there are numerous advantages of the various embodiments of the present invention. The apparatus, method and system embodiments of the present invention provide for high efficiency power amplification in broadband (or wideband) applications, such as 3G and other wideband cellular or RF applications, without significant bandwidth limitations, without intemodulation distortion, and without spectral growth. The various embodiments of the present invention effectively provide linear power amplification, minimizing any phase, gain, and other distortions. In addition, the apparatus, method and system of the present invention are cost-effective and capable of implementation in existing RF transmission systems, such as existing cellular base stations.
From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the novel concept of the invention. It is to be understood that no limitation with respect to the specific methods and apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.

Claims (10)

It is claimed:
1. A system for power amplification of an input signal to produce an amplified output signal, the system comprising:
an envelope detector, the envelope detector operable to determine an envelope detector voltage from the input signal;
a tracking power supply operably coupled to the envelope detector, the tracking power supply operable to determine a supply voltage from the envelope detector voltage;
an input signal conditioner operably coupled to the tracking power supply, the input signal conditioner operative, in response to the supply voltage, to determine a corresponding phase adjustment and a corresponding gain adjustment, the input signal conditioner further operative to modify the input signal using the corresponding phase adjustment and the corresponding gain adjustment to produce a conditioned input signal; and a power amplifier, the power amplifier operably coupled to the tracking power supply for reception of the supply voltage and operably coupled to the input signal conditioner to amplify the conditioned input signal to produce the amplified output signal.
2. The system of claim 1, further comprising:
a first delay circuit operably coupled to the input signal conditioner to synchronize the input signal to the supply voltage from the tracking power supply.
3. The system of claim 1, further comprising:
a second delay circuit operably coupled to the tracking power supply to synchronize the supply voltage to the conditioned input signal from the input signal conditioner.
4. The system of claim 1, wherein the tracking power supply is further operative to determine the supply voltage as a substantially quantized version of the envelope detector voltage.
5. The system of claim 1, wherein the amplified output signal is a substantially linear replica of the input signal.
6. A method for power amplification of an input signal to produce an amplified output signal, the method comprising:
(a) envelope detecting the input signal to determine an envelope detector voltage;
(b) determining a supply voltage from the envelope detector voltage;
(c) in response to the supply voltage, determining a corresponding phase adjustment and a corresponding gain adjustment;
(d) modifying the input signal using the corresponding phase adjustment and the corresponding gain adjustment to produce a conditioned input signal; and (e) using the supply voltage, amplifying the conditioned input signal to produce the amplified output signal.
7. The method of claim 6, wherein step (d) further comprises:
synchronizing the input signal to the supply voltage.
8. The method of claim 6, wherein step (e) further comprises:
synchronizing the supply voltage to the conditioned input signal.
9. The method of claim 6, wherein the supply voltage is determined as a substantially quantized version of the envelope detector voltage.
10. The method of claim 6, wherein the amplified output signal is a substantially linear replica of the input signal.
CA2435310A 2001-01-18 2001-12-18 High efficiency wideband linear wireless power amplifier Expired - Fee Related CA2435310C (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US09/765,747 2001-01-18
US09/765,747 US6735419B2 (en) 2001-01-18 2001-01-18 High efficiency wideband linear wireless power amplifier
PCT/US2001/049343 WO2002058249A2 (en) 2001-01-18 2001-12-18 High efficiency wideband linear wireless power amplifier

Publications (2)

Publication Number Publication Date
CA2435310A1 CA2435310A1 (en) 2002-07-25
CA2435310C true CA2435310C (en) 2010-03-23

Family

ID=25074373

Family Applications (1)

Application Number Title Priority Date Filing Date
CA2435310A Expired - Fee Related CA2435310C (en) 2001-01-18 2001-12-18 High efficiency wideband linear wireless power amplifier

Country Status (7)

Country Link
US (1) US6735419B2 (en)
EP (1) EP1417770A2 (en)
KR (1) KR20030076618A (en)
AU (1) AU2002243348A1 (en)
CA (1) CA2435310C (en)
IL (2) IL157023A0 (en)
WO (1) WO2002058249A2 (en)

Families Citing this family (63)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7409004B2 (en) * 2001-06-19 2008-08-05 Matsushita Electric Industrial Co., Ltd. Hybrid polar modulator differential phase Cartesian feedback correction circuit for power amplifier linearization
US7991071B2 (en) * 2002-05-16 2011-08-02 Rf Micro Devices, Inc. AM to PM correction system for polar modulator
US7801244B2 (en) * 2002-05-16 2010-09-21 Rf Micro Devices, Inc. Am to AM correction system for polar modulator
JP4230238B2 (en) * 2003-02-06 2009-02-25 パナソニック株式会社 Transmitting apparatus and adjustment method thereof
GB2398648B (en) 2003-02-19 2005-11-09 Nujira Ltd Power supply stage for an amplifier
US7353169B1 (en) * 2003-06-24 2008-04-01 Creative Technology Ltd. Transient detection and modification in audio signals
EP1650864A4 (en) * 2003-07-25 2006-06-28 Matsushita Electric Ind Co Ltd Amplification apparatus
US7126999B2 (en) * 2003-08-11 2006-10-24 Telefonaktiebolaget Lm Ericsson (Publ) Pseudo-polar modulation for radio transmitters
US6812876B1 (en) * 2003-08-19 2004-11-02 Broadcom Corporation System and method for spectral shaping of dither signals
US7970144B1 (en) 2003-12-17 2011-06-28 Creative Technology Ltd Extracting and modifying a panned source for enhancement and upmix of audio signals
FI20040139A0 (en) * 2004-01-30 2004-01-30 Nokia Corp Electronic circuit
US7440733B2 (en) * 2004-04-09 2008-10-21 Powerwave Technologies, Inc. Constant gain nonlinear envelope tracking high efficiency linear amplifier
US7593483B2 (en) * 2004-05-07 2009-09-22 Broadcom Corporation Nonlinear mapping in digital-to-analog and analog-to-digital converters
GB0418944D0 (en) * 2004-08-25 2004-09-29 Siemens Ag Method for envelope clipping
US7706467B2 (en) 2004-12-17 2010-04-27 Andrew Llc Transmitter with an envelope tracking power amplifier utilizing digital predistortion of the signal envelope
DE102005004370A1 (en) * 2005-01-31 2006-08-10 Infineon Technologies Ag Digital subscriber line-transmitting signal generating method, involves dividing bandwidth of input signal into frequency bands, transferring partial signals to line drivers and combining output signals of drivers to transmitting signal
US7460843B2 (en) * 2005-03-17 2008-12-02 Panasonic Corporation Amplifier apparatus, polar modulation transmission apparatus and wireless communication apparatus
US8224265B1 (en) 2005-06-13 2012-07-17 Rf Micro Devices, Inc. Method for optimizing AM/AM and AM/PM predistortion in a mobile terminal
EP1935026A1 (en) 2005-10-12 2008-06-25 Acco Insulated gate field-effet transistor having a dummy gate
US7454179B1 (en) 2005-11-15 2008-11-18 Rf Micro Devices, Inc. Radio frequency power detector and decision circuit used with DC supply voltage controlled power amplifiers
US20080285682A1 (en) * 2005-11-29 2008-11-20 Trda, Inc. Calibration apparatus and method for quadrature modulation system
US7877060B1 (en) 2006-02-06 2011-01-25 Rf Micro Devices, Inc. Fast calibration of AM/PM pre-distortion
US8093946B2 (en) 2006-03-17 2012-01-10 Nujira Limited Joint optimisation of supply and bias modulation
US20070223621A1 (en) * 2006-03-21 2007-09-27 M/A-Com, Inc. Method and apparatus for signal power ramp-up in a communication transmission
US7962108B1 (en) 2006-03-29 2011-06-14 Rf Micro Devices, Inc. Adaptive AM/PM compensation
US9622190B2 (en) 2006-07-25 2017-04-11 Google Technology Holdings LLC Spectrum emission level variation in schedulable wireless communication terminal
US7620377B2 (en) * 2006-08-30 2009-11-17 General Dynamics C4 Systems Bandwidth enhancement for envelope elimination and restoration transmission systems
WO2008115284A2 (en) 2006-10-16 2008-09-25 Thx Ltd. Loudspeaker line array configurations and related sound processing
US7889810B2 (en) * 2006-12-15 2011-02-15 Pine Valley Investments, Inc. Method and apparatus for a nonlinear feedback control system
US20080169951A1 (en) * 2007-01-17 2008-07-17 Stmicroelectronics, Inc. Direct digital synthesis of transmitter gain and bias control curves
US8009765B2 (en) * 2007-03-13 2011-08-30 Pine Valley Investments, Inc. Digital polar transmitter
US7869543B2 (en) * 2007-03-13 2011-01-11 Pine Valley Investments, Inc. System and method for synchronization, power control, calibration, and modulation in communication transmitters
US8009762B1 (en) 2007-04-17 2011-08-30 Rf Micro Devices, Inc. Method for calibrating a phase distortion compensated polar modulated radio frequency transmitter
EP2056451A3 (en) * 2007-10-16 2011-11-30 THX Ltd Efficient power amplifier
US8081710B2 (en) * 2007-11-08 2011-12-20 Pine Valley Investments, Inc. System and method for corrected modulation with nonlinear power amplification
US7983359B2 (en) * 2008-02-07 2011-07-19 Pine Valley Investments, Inc. Synchronization techniques for polar transmitters
US9240402B2 (en) 2008-02-13 2016-01-19 Acco Semiconductor, Inc. Electronic circuits including a MOSFET and a dual-gate JFET
US7969243B2 (en) 2009-04-22 2011-06-28 Acco Semiconductor, Inc. Electronic circuits including a MOSFET and a dual-gate JFET
US7863645B2 (en) * 2008-02-13 2011-01-04 ACCO Semiconductor Inc. High breakdown voltage double-gate semiconductor device
US8928410B2 (en) 2008-02-13 2015-01-06 Acco Semiconductor, Inc. Electronic circuits including a MOSFET and a dual-gate JFET
US8233852B2 (en) * 2008-04-04 2012-07-31 Pine Valley Investments, Inc. Calibration techniques for non-linear devices
US8081711B2 (en) * 2008-04-04 2011-12-20 Panasonic Corporation Predistortion methods and apparatus for polar modulation transmitters
MY176605A (en) 2009-02-25 2020-08-18 Thx Ltd Low dissipation amplifier
US7952431B2 (en) * 2009-08-28 2011-05-31 Acco Semiconductor, Inc. Linearization circuits and methods for power amplification
US8489042B1 (en) 2009-10-08 2013-07-16 Rf Micro Devices, Inc. Polar feedback linearization
US8159296B2 (en) * 2009-12-30 2012-04-17 Motorola Mobility, Inc. Method and apparatus for a power supply modulator linearizer
US8532584B2 (en) 2010-04-30 2013-09-10 Acco Semiconductor, Inc. RF switches
KR101763410B1 (en) * 2010-12-21 2017-08-04 한국전자통신연구원 Digital Pre-distortion Power Amplifier and Method for Controlling Sync Digitally thereof
KR101213778B1 (en) * 2011-01-11 2012-12-18 (주)펄서스 테크놀러지 Variable voltage digital audio amplication apparatus for noise compensation and method thereof
US9565655B2 (en) 2011-04-13 2017-02-07 Google Technology Holdings LLC Method and apparatus to detect the transmission bandwidth configuration of a channel in connection with reducing interference between channels in wireless communication systems
GB2507096B (en) * 2012-10-19 2016-03-23 Cirrus Logic Int Semiconductor Ltd Digital/analogue conversion
US8874052B2 (en) 2012-11-15 2014-10-28 Motorola Mobility Llc Method and apparatus for improving efficiency and distortion leakage in a wireless power amplifier
WO2014088792A1 (en) 2012-12-04 2014-06-12 Motorola Mobility Llc Spectrum emission level variation in schedulable wireless communication terminal
US9680434B2 (en) * 2012-12-28 2017-06-13 Mediatek, Inc. Method and apparatus for calibrating an envelope tracking system
US8824981B2 (en) * 2013-01-31 2014-09-02 Intel Mobile Communications GmbH Recalibration of envelope tracking transfer function during active transmission
US9484860B2 (en) 2013-03-12 2016-11-01 Thx Ltd. Tracking power supply with increased boost capability
US8909180B1 (en) 2013-06-26 2014-12-09 Motorola Solutions, Inc. Method and apparatus for power supply modulation of a radio frequency signal
US9362868B2 (en) * 2013-12-02 2016-06-07 Futurewei Technologies, Inc. Reduced power amplifier load impact for open loop envelope tracking
WO2015187072A1 (en) * 2014-06-04 2015-12-10 Telefonaktiebolaget L M Ericsson (Publ) Method and controllable delay unit for managing amplitude slope and phase slope of an input signal
DE102014119625A1 (en) * 2014-12-23 2016-06-23 Intel IP Corporation Circuit and method for providing a radio frequency signal
US9998241B2 (en) * 2015-02-19 2018-06-12 Mediatek Inc. Envelope tracking (ET) closed-loop on-the-fly calibration
DE102015110238A1 (en) 2015-06-25 2016-12-29 Intel IP Corporation A circuit and method for generating a radio frequency signal
WO2024035495A1 (en) * 2022-08-11 2024-02-15 Qorvo Us, Inc. Power management circuit

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5935522B2 (en) * 1979-10-16 1984-08-29 ヤマハ株式会社 power amplifier
US4521742A (en) * 1981-12-04 1985-06-04 Nad Holding Limited Amplifier power supply with large dynamic headroom
JPH03198512A (en) * 1989-12-27 1991-08-29 Mitsubishi Electric Corp High frequency amplifier
JPH0440105A (en) * 1990-06-06 1992-02-10 Oki Electric Ind Co Ltd Linear amplifier circuit
US5420536A (en) * 1993-03-16 1995-05-30 Victoria University Of Technology Linearized power amplifier
IT1265271B1 (en) * 1993-12-14 1996-10-31 Alcatel Italia BASEBAND PREDISTRITORTION SYSTEM FOR THE ADAPTIVE LINEARIZATION OF POWER AMPLIFIERS
US5742201A (en) * 1996-01-30 1998-04-21 Spectrian Polar envelope correction mechanism for enhancing linearity of RF/microwave power amplifier
US5936464A (en) 1997-11-03 1999-08-10 Motorola, Inc. Method and apparatus for reducing distortion in a high efficiency power amplifier
US6107880A (en) 1998-08-06 2000-08-22 Motorola, Inc. Method and apparatus for increasing the linearity of the phase and gain of a power amplifier circuit
US6107872A (en) * 1998-11-03 2000-08-22 Harris Corporation Adaptive control of RF power amplifier power supply voltage
US6043707A (en) 1999-01-07 2000-03-28 Motorola, Inc. Method and apparatus for operating a radio-frequency power amplifier as a variable-class linear amplifier
US6157253A (en) 1999-09-03 2000-12-05 Motorola, Inc. High efficiency power amplifier circuit with wide dynamic backoff range
WO2001067598A1 (en) * 2000-03-10 2001-09-13 Paragon Communications Ltd. Method and apparatus for improving the efficiency of power amplifiers, operating under a large peak-to-average ratio

Also Published As

Publication number Publication date
IL157023A0 (en) 2004-02-08
KR20030076618A (en) 2003-09-26
US6735419B2 (en) 2004-05-11
IL157023A (en) 2013-12-31
US20020094795A1 (en) 2002-07-18
WO2002058249A2 (en) 2002-07-25
WO2002058249A3 (en) 2004-02-26
CA2435310A1 (en) 2002-07-25
AU2002243348A1 (en) 2002-07-30
EP1417770A2 (en) 2004-05-12

Similar Documents

Publication Publication Date Title
CA2435310C (en) High efficiency wideband linear wireless power amplifier
US6600369B2 (en) Wideband linear amplifier with predistortion error correction
KR101139576B1 (en) Improved power amplifier configuration
US7440733B2 (en) Constant gain nonlinear envelope tracking high efficiency linear amplifier
US7068984B2 (en) Systems and methods for amplification of a communication signal
US9680434B2 (en) Method and apparatus for calibrating an envelope tracking system
US7259630B2 (en) Elimination of peak clipping and improved efficiency for RF power amplifiers with a predistorter
KR20060039454A (en) Dynamic bias for rf power amplifiers
US5781069A (en) Pre-post distortion amplifier
WO2008019286A2 (en) System and method for low delay corrective feedback power amplifier control
EP1518320B1 (en) Efficient generation of radio frequency currents
US20020047746A1 (en) Method for linearizing, over a wide frequency band a transmission chain comprising a power amplifier
US6507244B2 (en) Transmitter with a sliding compression point
WO2004054096A1 (en) Preserving linearity of an isolator-free power amplifier by dynamically adjusting bias and supply of active devices
KR100370545B1 (en) A high power type pre-distorting apparatus for reducing spurious signal in high frequency band linear power amplifier
US20030008683A1 (en) Base-station amplifier device
US7050770B1 (en) Linearized amplifier having a bypass circuit
KR100320427B1 (en) Method and Device for Compensation of Distortion Signal in Communication System
EP1594222A1 (en) Operating point adjusting method and power amplifier circuit

Legal Events

Date Code Title Description
EEER Examination request
MKLA Lapsed

Effective date: 20161219