Amplifiers – Hum or noise or distortion bucking introduced into signal...
Patent
1993-12-21
1994-12-20
Mottola, Steven
Amplifiers
Hum or noise or distortion bucking introduced into signal...
330136, H03F 130, H03G 332
Patent
active
053748964
ABSTRACT:
A high-frequency power amplifier in which the negative feedback control system linearity is maintained and non-linear distortion is stably compensated has: a variable gain circuit, disposed as a prestage of the power amplifier, in which the control voltage vs. gain characteristic is an inverse logarithm characteristic, which performs variable control on the level of the input signal supplied to the power amplifier; a gain detecting circuit, which detects the combined gain of the high frequency power amplifier and the variable gain circuit; and a loop filter, which supplies the output signal of this gain detecting circuit to the variable gain circuit as a control voltage. This gain detecting circuit includes: a first logarithmic convertor circuit, which performs logarithmic conversion on an envelope detection signal of the signal inputted into the variable gain circuit; a second logarithmic convertor circuit, which performs logarithmic conversion on an envelope detection signal of the output signal of the high-frequency power amplifier; and a subtraction circuit, which outputs the differential, or subtraction, signal of the output signals of the first and second logarithmic conversion circuits.
REFERENCES:
patent: 4188587 (1980-02-01), Palmer
patent: 4263560 (1981-04-01), Ricker
Telecommunications and Radio Engineering, vol. 44, No. 4, Apr. 1989, Washington, pp. 98-100, V. G. Lavrushenkov et al.: "The Features of Using Balanced Envelope Feedback in Power Amplifiers."
Patent Abstracts of Japan, vol. 9, No. 240 (E-245) (1963), 26 Sep. 1985, & JP-A-60 090 409 (Matshushita Denki Sangyo K.K.), 21 May 1985.
Patent Abstracts of Japan, vol. 12, No. 3 (E-570), 7 Jan. 1988 & JP-A-62 163 407 (Hitachi Ltd.), 20 Jul. 1991.
Patent Abstracts of Japan, vol. 15, No. 387 (E-1117), 30 Sep. 1991 & JP-A-03 155 210 (NEC Corp), 3 Jul. 1991.
Iida Sachio
Sato Hideaki
Mottola Steven
Sony Corporation
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