A 1.8 V pseudo-differential switched-capacitor amplifier

A switched-capacitor amplifier (SCA), for a 1.8 V, 10 bit, 2.5 Ms/sec data converter has been developed. For the SCA to settle within 0.05% at 2.5 Ms/sec rate, a pseudo-differential core amplifier, consisting of two fully cascoded amplifiers with gain-enhancement is proposed. A switching scheme is used for offset cancellation and, simultaneously, for the capacitive level shifting needed to bias the gain-enhancement amplifiers. The core amplifier offers 100 dB gain, more than 100 MHz unity-gain frequency with 1.8 V supply. The SCA sinks 1.25 mA at 1.8 V and has a closed loop gain of 2. It was fabricated in a 1.2 /spl mu/m CMOS process. Functionality and performance were verified.