Polar envelope correction mechanism for enhancing linearity of RF/microwave power amplifier

a technology of linearity and correction mechanism, applied in the field of communication systems, can solve the problems of inapplicability of baseband correction techniques using baseband signals, inability to achieve practical solutions for correcting distortion, and inability to use conventional correction mechanisms such as feed forward or predistortion schemes, etc., to achieve the effect of improving linearity of non-linear microwave/rf power amplifiers, simple, efficient and effective, and reducing the bandwidth of digital modulation

Inactive Publication Date: 2001-10-16
INTEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention takes advantage of the relatively modest bandwidth of digital modulation formats such as those shown in Table 1, by providing an amplitude and phase distortion correction strategy that is based upon signal envelope feedback. In particular, the present invention provides a simple, yet efficient and effective way of improving the linearity of a non-linear microwave/RF power amplifier employed for digital modulation formats having signal bandwidths in the KHz to low MHz range, through the use of a polar envelope-...

Problems solved by technology

Unfortunately, conventional correction mechanisms, such as feed forward or predistortion schemes, are complex, inefficient, and prohibitively expensive to be practical solutions for correcting distortion in the majority of single ...

Method used

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  • Polar envelope correction mechanism for enhancing linearity of RF/microwave power amplifier
  • Polar envelope correction mechanism for enhancing linearity of RF/microwave power amplifier
  • Polar envelope correction mechanism for enhancing linearity of RF/microwave power amplifier

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first embodiment

FIG. 17 schematically illustrates a circuit implementation of the high speed phase / amplitude controller 125 of FIG. 4, configured as a differential peak detector 240 for envelope amplitude comparison and a phase bridge 250 serving as a phase detector. In the differential peak detector 240, input signals are coupled to respective R (reference) and M (measure) input ports 123 and 124 through respective dc blocking capacitors 245 and 246, resistors 251 and 253 and peak detector diodes 255 and 256 to (-) and (+) input ports 257 and 258 of differential amplifier 260. The (+) and (-) input ports 257 and 258 of differential amplifier 260 are further coupled through respective capacitors 265 and 266 and resistors 271 and 273 to ground. Isolation resistors 251 and 253, detector diodes 255 and 256, by-pass capacitors 265, 266 and video load resistors 271 and 273 comprise a pair of fast biased peak detectors which measure the amplitude of the envelopes of the signals delivered to the R and M p...

second embodiment

FIG. 18 schematically illustrates a circuit implementation of the high speed phase / amplitude controller 125 of FIG. 4, configured with peak detectors and a Gilbert multiplier. In the embodiment of FIG. 18, the R and M input terminals 123 and 124, respectively, are each split into two paths by quadrature power divider 311 and in phase power divider 312. The in phase R paths and one of the M paths are each peak detected by means of a pair of matched, biased diode detectors 321 and 322, respectively, and coupled to (+) and (-) inputs 331 and 332 of differential amplifier 330. The output of differential amplifier 330 is the control voltage V.sub.A.

The control voltage V.sub..PHI. is obtained by multiplying the remaining quadrature R and in phase M signals limited by respective phase-matched limiters 341 and 343 in a wideband Gilbert cell multiplier 350 and low pass filtering the result by means of a low pass filter 352. The phase matched limiters 341 and 343 remove amplitude information ...

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Abstract

Linearity of an RF/microwave power amplifier is enhanced by an amplitude and phase distortion correction mechanism based upon signal envelope feedback, that operates directly on the RF signal passing through the power amplifier. A phase-amplitude controller responds to changes in gain and phase through the RF/microwave power amplifier signal path caused by changes in RF input power, DC power supply voltages, time, temperature and other variables, and controls the operation of a gain and phase adjustment circuit, so as to maintain constant gain and transmission phase through the RF/microwave power amplifier.

Description

FIELD OF THE INVENTIONThe present invention relates in general to communication systems, and is particularly directed to a polar envelope responsive correction mechanism for reducing amplitude and phase distortion in a microwave and RF power amplifier that is designed to amplify signals whose bandwidth is in the KHz to low MHz spectral range.BACKGROUND OF THE INVENTIONAs the wireless communications market continues to expand, the accompanying need for increased capacity is forcing a move from analog modulation techniques, such as frequency modulation (FM), to digital modulation formats, such as time division multiple access (TDMA) and code division multiple access (CDMA), which have bandwidths listed in Table 1.TABLE 1 US DAMPs (TDMA) 30 kHz GSM 277 kHz CDMA 1.23 MHzBoth TDMA and CDMA modulation require somewhat greater linearity than can be routinely obtained in an uncorrected, high efficiency class AB power amplifier. Unfortunately, conventional correction mechanisms, such as feed...

Claims

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Application Information

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IPC IPC(8): H03F1/32H03G1/00
CPCH03F1/3247H03F1/3282H03F2200/438H03F2200/57H03G1/0064H03G1/007H03F1/32
Inventor EISENBERG, JOHN A.BASKIN, BRIAN L.ROBERTSON, III, CHARLES STUARTSTATEZNI, DIETER WERNERMUCENIEKS, LANCE TODDBRUBAKER, DAVID LEE
Owner INTEL CORP
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