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The performance of high unity gain-bandwidth current gain-based CMOS operational amplifiers fabricated in a 1.5-μm CMOS digital process is discussed. High unity-gain bandwidth was achieved by using short-channel MOS transistors operating in the current gain mode. Stacked current mirrors have been utilized as current gain stages to minimize the effects of the channel-length modulation in short-channel MOS transistors. Open-circuit gain of 60 to 70 dB, a unity-gain bandwidth of 70 to 100 MHz, and slew-rate of 200 V/μs were demonstrated at a DC power dissipation of 1-2 mW.