CMOS transimpedance amplifier with controllable gain for RF overlay

In this paper, a fully-differential transimpedance amplifier (TIA) with controllable transimpedance for use in RF overlay downstream communication systems is presented. It consists of a shunt-shunt feedback transimpedance amplifier with transimpedance and open loop gain control. The transimpedance amplifier is intended for 47 MHz to 870 MHz subcarrier multiplexed RF signals with a 18 dBΩ transimpedance gain control range. The TIA, designed in a CMOS 180 nm technology, dissipates 27 mW from a supply voltage of 1.8 V. The input-referred noise current is lower than 6 pA/√Hz to allow an optical input power from -6 to +2 dBm.