A CMOS IF transceiver with 90 dB linear control VGA for IMT-2000 application

Design of variable gain amplifier in CMOS technology

“…VGA is usually used in a feedback loop to form the AGC circuit, and is to produce a known output voltage magnitude with various input signal levels [50]. In an AGC loop, an exponential gain control, or dB-linear characteristic, may be required to maintain the settling time independent of the input signal levels and to achieve a large gain variation range [51].…”