Predistortion circuit, low-distortion power amplifier, and control methods therefor

• US 7,081,795 B2
• Filed: 10/24/2005
• Issued: 07/25/2006
• Est. Priority Date: 05/30/2000
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsuura, Toru, Sakakura, Makoto, Ishida, Kaoru, Fujiwara, Seiji
• Primary Examiner(s): Choe, Henry
• Application Number:
  US11/255,998
• Publication Number:
  US 20060061418A1
• Time in Patent Office: 274 Days
• Field of Search: 330/149, 330/280, 330/290, 330/303, 375/297, 455/63
• US Class Current: 330/149
• CPC Class Codes: H03F 1/3229 using a loop for error extraction and another loop for error subtraction
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3276 using the nonlinearity inherent to components, e.g. a diode
• CPC Class Codes: H03F 1/3282 Acting on the phase and the amplitude of the input signal

Abstract

An amplitude frequency characteristic adjustment circuit 106 is provided downstream of and connected to a distortion generation circuit 105. An amplitude difference between low-frequency-side and high-frequency-side distortion voltages is adjusted by the amplitude frequency characteristic adjustment circuit 106, and then their amplitudes and phases are adjusted by a vector adjustment circuit 107. This configuration makes it possible to suppress simultaneously both of low-frequency-side and high-frequency-side distortion voltages of a distortion generated by a wide-band class-AB power amplifier even if they are different in amplitude and phase.

Claims

1. A low-distortion power amplifier comprising:

a combining circuit for combining an input signal with another signal;

a power amplifier for receiving an output signal of the combining circuit;

a divider for branching an output signal of the power amplifier into plural branched signals;

a distortion extraction circuit for extracting a distortion signal from one of the branched signals;

at least two filter circuits for separating the distortion signal into distortion signals having different frequencies; and

at least two vector adjustment circuits for varying amplitudes and phases of the distortion signals that are output from the respective filter circuits,

wherein a signal obtained by combining together output signals of the vector adjustment circuits is input to the combining circuit as said another signal and the other branched signal is output from the low-distortion power amplifier.

2. The control method for the low-distortion power amplifier according to claim 1, comprising the steps of:

detecting a magnitude of the distortion signal that is output from the distortion extraction circuit; and

controlling at least one of the amplitude frequency characteristic adjustment circuit or circuits and the vector adjustment circuit or circuits so as to minimize the detected magnitude of the distortion signal.