A temperature stable CMOS variable gain amplifier with 80-dB linearly controlled gain range

An IF variable gain amplifier with a quadrature demodulator is fabricated using a 0.25-/spl mu/m CMOS technology. An 80-dB linearly controlled gain range is achieved with exponential voltage-to-current converters using MOS transistors biased in a subthreshold exponential region. To avoid the temperature dependence of the gain control characteristic, a master-slave control technique is adopted for the exponential voltage-to-current converters. The experimental results indicate that the proposed technique is effective for a CMOS VGA.