Design of 0.4 V Operational Amplifier Using Low-Power Techniques

In this paper a low-power/low-voltage CMOS operational amplifier (op amp) using sub-threshold region of MOSFET for bio-medical instrumentation operating with a 0.4 V supply is described. A two stage operational amplifier is designed and simulated using 0.18 ?m CMOS technology. Two types of low-power/low-voltage design techniques (a) bulk-driven (b) dynamic threshold voltage MOSFET (DTMOS) are used. With bulk-driven technique, the open loop gain is 69.88 dB, the unity gain-bandwidth (UGBW) is 87.1 kHz, the CMRR obtained is 83 dB and phase margin is 88.78 degree with 10pF load. The power consumption is 1.8 ?W. With DTMOS technique, the open loop gain is 83.31 dB, the unity gain-bandwidth is 758.6 kHz, the CMRR obtained is 157.1 dB and the phase margin is 71.5 degree with 10pF load. The power consumption is 1.8 ?W. The DTMOS technique provides high unity gain-bandwidth and high open loop gain as compared to bulk-driven technique.