A Wideband CMOS Variable Gain Amplifier with a Novel Linear-in-dB Gain Control Structure

In this paper, a novel structure of linear-in-dB gain control is introduced. Based on this structure, a wideband variable gain amplifier has been designed and implemented in TSMC 0.18-mum RF CMOS process. On-chip measured results show a good linear-in-dB gain control characteristic with 12.8 dB dynamic gain range of -3.3~9.5 dB. It can operate in the frequency range of 43~2330 MHz and consumes 16.2 mW at 1.8 V supply. The noise figure is 6.2 dB at maximum gain and the input P1dB at minimum gain is -9 dBm.