A CMOS 12-bit 4 MHz pipelined A/D converter with commutative feedback capacitor

A 2-bit/stage CMOS 12-bit 4 MHz pipelined A/D converter (ADC) using commutated feedback capacitor switching scheme is presented. The technique improves the DNL without using complicated calibration circuitry, nor requiring extra calibration cycle. Approximately, only 7-bit matched capacitors are required for 12-bit ADC's. Very high output swing is achieved in a gain enhanced folded cascode amplifier by operating output stage transistors in the triode region. This 12-bit pipelined ADC is integrated in a standard 0.8 /spl mu/m single poly, triple metal CMOS process, and dissipates 45 mW.