Class AB output stages for low voltage CMOS opamps with accurate quiescent current control by means of dynamic biasing

Two new class AB output stages for CMOS op-amps are proposed with accurate quiescent current control. The second proposed stage also provides accurate control of the minimum current through the output transistors. The proposed stages can be operated with a supply voltage close to a transistor threshold voltage. A dynamic biasing scheme allows them to operate in a wide range of supply voltages. Using these stages two opamps have been designed using a 0.8 mum CMOS technology. Experimental results show a unity gain frequency of 15 MHz with 290 muA of quiescent current and a 10 pF load, using a 1.5 V single voltage supply.