Variable gain amplifier with improved control...

Details Variable gain amplifier with improved control... Variable gain amplifier with improved control...

2007-08-21

2007-08-21

Pascal, Robert (Department: 2817)

Amplifiers

With semiconductor amplifying device

Including gain control means

Reexamination Certificate

active

10524182

ABSTRACT:
A variable-impedance device is placed in parallel with the input to a variable-gain amplifier, and is controlled so as to provide a substantially constant load impedance to a source. Preferably, the variable-impedance device includes a diode with a variable bias current. This diode bias current is adjusted inversely with the amplifier bias current, such that the parallel sum of the two input path impedances remains approximately constant across a wide range of gain. This variable gain amplifier system is particularly well suited for use in a wireless transmitter, or cellular telephone.

REFERENCES:
patent: 5999056 (1999-12-01), Fong
patent: 6211737 (2001-04-01), Fong
patent: 6281754 (2001-08-01), Mizunaga
patent: 6351188 (2002-02-01), Masahiro
patent: 1 071 204 (2001-01-01), None
patent: 1 093 222 (2001-04-01), None

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