Variable gain amplifier

Details Variable gain amplifier Variable gain amplifier

2005-05-10

2005-05-10

Lam, Tuan T. (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Specific signal discriminating without subsequent control

By amplitude

C327S065000, C327S563000

Reexamination Certificate

active

06891405

ABSTRACT:
The present invention provides systems and methods related to a variable gain amplifier. The variable gain amplifier includes a first differential amplifier, a second differential amplifier, a combining circuit, and a current control circuit. The first differential amplifier circuit and the second differential amplifier circuit share a common input signal and have different amplification degrees. Each of the first and second differential amplifier circuits includes a first transistor and a second transistor that form a differential pair. The first transistor and the second transistor of each differential amplifier circuit have bases that are supplied with the input signal, and collectors that output signals to the combining circuit. The current control circuit changes a ratio between a bias current of the first differential amplifier circuit and a bias current of said second differential amplifier circuit based on a gain control signal.

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patent: 5043602 (1991-08-01), Flannagan
patent: 5999044 (1999-12-01), Wohlfarth et al.
patent: 0 317 759 (1988-10-01), None
patent: 0 730 345 (1996-09-01), None
Integrated Electronics: Analog and Digital circuits and systems, Jacob Millman and Christo C. Halkias, McGraw-Hill, 1972.*
European Search Report.

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