High performance CMOS operational-amplifier

The design of a high-performance CMOS operational-amplifier (op-amp) in 3- mu m double-level-metal technology is presented. The amplifier makes use of stacked (cascode) current source techniques and an enhanced push-pull output stage. This op-amp will be used for the realization of high-frequency switched-capacitor (SC) filters. SPICE simulations of the op-amp show a unity gain bandwidth of 40 MHz and a DC gain of 72 dB when using a bias current of 100 mu A and a load capacitance of 15 pF. A test chip implementing the op-amp and other analog test cells was fabricated. Test results from the fabricated device demonstrate a DC gain of about 67 dB, with a unity gain bandwidth of about 40 MHz and a 36 V/ mu s slew rate when using a bias current of about 100 mu A and a 15-pF load.<>