A 0.7-V Opamp in Scaled Low-Standby-Power FinFET Technology

摘要

This paper demonstrates a FinFET operational amplifier (opamp), which is suitable, to be integrated with digital circuits in a scaled low-standby-power (LSTP) technology and operates at extremely low voltage. The opamp is consisting of an adaptive threshold-voltage (V_t) differential pair and a low-voltage source follower using independent-double-gate-(IDG-) FinFETs. These two components enable the opamp to extend the common-mode voltage range (CMR) below the nominal V_t even if the supply voltage is less than 1.0 V. The opamp was implemented by our FinFET technology co-integrating common-DG- (CDG-) and IDG-FinFETs. More than 40-dB DC gain and 1-MHz gain-bandwidth product in the 500-mV-wide input CMR at the supply voltage of 0.7 V was estimated with SPICE simulation. The fabricated chip successfully demonstrated the 0.7-V operation with the 480-mV-wide CMR, even though the nominal V_t was 400 mV.