A low-voltage class-AB OTA exploiting adaptive biasing

We present a low voltage approach to design an adaptive bias circuit for a class-AB input stage, and exploit it to design a fully-differential 0.6 V class-AB symmetrical OTA that also features cascode dynamic biasing and a class-AB CMFB circuit. Simulations in 0.13 μm CMOS technology show a 42x increase of the bias current when signal is applied, that yields a faster settling time with respect to a class-A OTA designed with the same static current. The OTA provides 43.6 dB gain and good large-signal FOM when compared with sub-1 V OTAs in the literature, and is still operational at 0.4 V supply voltage.