A low-voltage programmable-gain current-mode amplifier

A CMOS low-voltage, wide-band continuous-time current amplifier is presented. Based on an open-loop topology, the circuit is composed by transresistance and transconductance stages built around triode-operating transistors. In addition to an extended dynamic range, the amplifier gain can be programmed within good accuracy by the rapport between the aspect-ratio of such transistors and tuning biases V_X and V_Y. A balanced current-amplifier according to a single 1.1 V-supply and a 0.35 μm fabrication process is designed. Simulated results from PSPICE and Bsim3v3 models indicate a programmable gain within the range 20-34 dB and a minimum break-frequency of 1 MHz @C_L=1 pF. For a 200 μA_pp-level, THD is 0.8% and 0.9% at 1 kHz and 100 kHz, respectively. Input noise is 405pA√(Hz) @20 dB-gain, which gives an SNR of 66 dB @1 MHz-bandwidth. Maximum quiescent power consumption is 56 μW.