Abstract
A large-swing, high-driving, low-power, class-AB buffer amplifier, which, consists of a high-gain input stage and a unity-gain class-AB output stage, with low variation of quiescent current is proposed. The low power consumption and low variation of the quiescent output current are achieved by using a weak-driving and a strong-driving pseudo-source followers. The high-driving capability is mainly provided by the strong-driving pseudo-source follower whose output transistors are turned off in the vicinity of the stable state to reduce the power consumption and the variation of output current, while the quiescent state is maintained by the weak-driving pseudo-source follower. The error amplifiers with source-coupled pairs of the same type transistors are merged into a single error amplifier to reduce the area of the buffer and the current consumption. An experimental prototype buffer amplifier implemented in a 0.35-μm CMOS technology demonstrates that the circuit dissipates an average static power consumption of only 388.7 μW with the standard deviation of only 3.4 μW, which is only 0.874% at a power supply of 3.3 V, and exhibits the slew rates of 2.18 V/μS and 2.50 V/μs for the rising and falling edges, respectively, under a 300 Ω/150 pF load. Both of the second and third harmonic distortions (HD2 and HD3) are -69 dB at 20 kHz under the same load.