A reconfigurable op-amp/DDA CMOS amplifier architecture

A simple architecture for a configurable op-amp or differential difference amplifier (DDA) is presented. The circuitry can be configured as an input/output rail to rail high-speed op-amp, or as a DDA. The circuit was simulated using SPICE and fabricated in a 2- mu m CMOS process through MOSIS. Configured as an op-amp, it achieves a positive and negative slew rate of 16 V/ mu s, a unity gain frequency of 14 MHz, and an open loop differential gain of 68 dB with a power consumption of 6 mW at 5-V supply. The circuit was also tested and found to work satisfactorily as a differential difference amplifier for frequencies up to about 10 MHz with a differential input range limited to 200 mV.<
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