Realization of 0.7-V analog circuits by adaptive-Vt operation of FinFET

An adaptive-threshold-voltage differential pair and a low-voltage source follower using independent-double-gate-(IDG-) FinFETs are proposed for a low-voltage operational amplifier (op amp). These circuits were implemented by our FinFET technology that enables co-integration of connected-DG- (CDG-) and IDG-FinFETs. The proposed components enable a two-stage op amp to accept the input below the nominal threshold voltage. More than 40-dB gain and 1-MHz GBW in the 500-mV-wide CM input range under 0.7-V supply voltage was estimated by SPICE simulation. Our preliminary silicon implementation demonstrated 0.7-V operation of the proposed source follower.