A Dual-Supply Two-Stage CMOS Op-amp for High-Speed Pipeline ADCs Application

In this brief, a dual-supply two-stage op-amp is proposed for a 12-b 1 GS/s pipeline ADC, which is composed of a low-voltage supply pre-amplifier and a high-voltage supply amplifier. Its closed-loop bandwidth reaches to 5.2 GHz, and the phase margin is larger than 60°. The closed-loop amplifier can settle to 99.95% accuracy within 230 ps, which satisfies the harsh requirements of the first-stage MDAC. The proposed op-amp was employed in a single-channel 12-b 1 GS/s pipeline ADC. The ADC is powered by 1.3 V and the op-amp is powered by dual-supply voltage of 1.3 V and 2.5 V. The ADC fabricated in 65 nm CMOS process consumes 360 mW at 1 GS/s. It achieves an SNDR of 61.9 dB and an SFDR of 72.6 dB with 30 MHz input signal, while maintaining an SNDR > 56.0 dB and SFDR > 69.0 dB in the entire 500 MHz Nyquist band.