Variable gain amplifier

Details Variable gain amplifier Variable gain amplifier

2008-05-13

2008-05-13

Nguyen, Khanh Van (Department: 2817)

Amplifiers

With semiconductor amplifying device

Including differential amplifier

C330S253000

Reexamination Certificate

active

07372330

ABSTRACT:
A variable gain amplifier of such configuration that can yield continuously and log-linearly variable gains in relation to control voltage and, at the same time, that does not use an attenuator, an element which otherwise would entail cause of increased noise. The amplifier includes a plurality of gm amplifiers connected in parallel with input signal, exponential multipliers connected respectively to the gm amplifiers, a control section to vary the multiplication coefficient of the exponential multipliers according to the external gain control signal, and an I-V converter circuit to aggregate current output after multiplication and convert the aggregated current output to voltage. A continuously variable gain characteristic can be obtained without the use of an attenuator but by varying multiplication coefficient according to control voltage.

REFERENCES:
patent: 5418494 (1995-05-01), Betti et al.
patent: 6084466 (2000-07-01), Phanse et al.
patent: 6175278 (2001-01-01), Hasegawa
patent: 7279984 (2007-10-01), Grillo et al.
patent: 11-177357 (1999-07-01), None
patent: 11-340760 (1999-12-01), None
patent: 2004-104269 (2004-04-01), None
Analog Devices, Inc., Data Sheet AD8332, “Ultralow Noise VGAs with Preamplifier and Programmable RIN” , pp. 1-32, © 2003.
Texas Instruments, Inc., Data Sheet VCA2616, “Dual, Variable-Gain Amplifier with Low-Noise Preamp”, pp. 1-19, © 2002-2004.

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