Abstract
A current-mode operational amplifier (COA) for low-voltage high-speed operation is proposed in this dissertation. This COA adopts the current-steering approach, which avoids using a current mirror as the transimpedance stage and improves the frequency response. On the other hand, a high-swing multiple-cascode structure is invoked to pull up the open-loop gain of the COA and to reduce the operating voltage. At last a modified input structure is proposed, which shortens the signal path from the input to the transconductance stage to achieve a higher unit gain bandwidth (UGBW). The proposed COA was simulated using HSPICE, level 28 parameters of TSMC 0.6- single-poly-triple-metal (1P3M) CMOS process. The simulated results showed that it has a higher open-loop gain (~93dB) and a high UGBW (~225MHz). But a larger input resistance of 17.6 results due to the introduction of the modified input structure. Besides, this COA operates under 1.5V power supply voltages with a power dissipation of about 3.9mW.