文档介绍：IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 32, NO. 12, DECEMBER 1997 2105
Brief Papers
A Power-Efficient, Low-Distortion Variable Gain
Amplifier Consisting of Coupled Differential Pairs
Pieter J. G. van Lieshout and Rudy J. van de Plassche
Abstract—A variable gain amplifier incorporating a plurality II. SYSTEM ARCHITECTURE
of coupled differential pairs has been designed in a bipolar
technology. By applying variable offset voltages to these differ-
ential pairs, the overall gain of the system can be varied. The A. Coupling of Differential Pairs
linear input region is inversely proportional to gain, making the Systems incorporating a plurality of coupled differential
amplifier very well suited for automatic gain control circuits.
Furthermore, the gain of the proposed amplifier is 0–25 dB, the pairs can be used to synthesize arbitrary transfer functions [3].
signal bandwidth is 35 MHz, and the output IP3 is 24–30 dBm. Fig. 1 shows an example of such a multi-tanh structure, here
It operates from a 5-V power supply and dissipates 40 mW. The used as a variable gain amplifier. The transfer function of each
P
active chip area is mm in a 1-" m bipolar technology. individual differential pair can be shifted by varying the
Index Terms— Bipolar, gain control, multi-tanh technique, corresponding offset voltage . The overall output current
transadmittance element, varia