Class-AB Fully Differential Voltage Followers

Two fully differential class-AB voltage followers with essentially enhanced slew rate are introduced. The first one is based on the crossquad cell. The second one is based on the conventional voltage follower. Class-AB operation with accurate control of the quiescent current and extended bandwidth is achieved in both cases with minimal additional circuitry, zero extra static power dissipation and without increasing supply requirements. Experimental results of a test chip fabricated in 0.5- CMOS technology show slew rate enhancement of over a factor 15 and large extension of the peak-to-peak input range.