Digitally Controlled VGA for Low Power Low-IF Receivers

A digitally controlled variable gain amplifier (VGA) for low power, low-IF receivers is presented. The amplifier was designed and fabricated in IBM 7WL BiCMOS 180 nm technology. It shows a dynamic range of 45 dB with a maximum gain of 52 dB and a minimum gain of 7 dB. The gain variation is achieved by means of switched feedback resistors. These are controlled by a demultiplexer and 4 control bits. The 1 dB compression corresponds to 9 dBm of input power in a 50 Omega system and the 3-dB-bandwith is approximately 10 MHz. The overall power consumption is 13 mW.