Bulk-driven gain-enhanced fully-differential amplifier for VT + 2Vdsat operation

A bulk-driven fully differential CMOS amplifier based on an active bootstrapped gain enhancement technique is introduced. The gain enhancement technique produces gains in excess of 100dB at supply voltages below VT + 2Vdsat in a two stage amplifier. The design constraints for obtaining maximum speed with this architecture are discussed. Simulations of the fully differential amplifier designed in an AMIS 0.35μm CMOS process with a class-AB output stage are shown and compared to other low-voltage amplifier architectures.