Abstract: A unity gain amplifier based on CMOS technology designed to drive a large capacitive load such as a piezoelectric speaker with a 5V power supply. The invention utilizes a rail-to-rail voltage range (i.e., ground to power supply voltage) at its input as well as at its output and is capable of entering into a power down mode, In this manner, it is possible to produce as a single application specific integrated circuit (ASIC), a circuit for converting a digital signal to an analog signal and amplifying the analog signal so as to be capable of driving a large capacitive load with a rail-to-rail dynamic range and which operates at low noise.