A Low-Voltage Wide-Swing Programmable-Gain Current Amplifier

A CMOS low-voltage, wide-swing continuous-time current amplifier is presented. Exhibiting an open-loop architecture, the circuit is composed of transresistance and transconductance stages built upon triode-operating transistors. In addition to an extended dynamic range, the current gain can be programmed within good accuracy by a rapport involving only transistor geometries and tuning biases. Low temperature-drift on gain setting is then expected. In accordance with a 0.35 μm n-well CMOS fabrication process and a single 1.1 V-supply, a balanced current-amplifier is designed for a programmable gain-range of 6–34 dB and optimized with respect to dynamic range. Simulated results from PSPICE and Bsim3v3 models indicate, for a 100 μApp-output current, a THD of 0.96 and 1.87% at 1 KHz and 100 KHz, respectively. Input noise is 120 pA√Hz @10 Hz, with S/N e 63.2 dB @1%-THD. At maximum gain, total quiescent consumption is 334 μW. Measurements from a prototyped amplifier reveal a gain-interval of 4.8–33.1 dB and a maximum current swing of 120 μApp. The current-amplifier bandwidth is above 1 MHz.