A 13-ENOB, 5 MHz BW, 3.16 mW multi-bit continuous-time ΔΣ ADC in 28 nm CMOS with excess-loop-delay compensation embedded in SAR quantizer

A 13-ENOB, 5 MHz BW, 3.16 mW 3-bit continuous-time ΔΣ ADC sampling at 432 MHz is presented. For power efficiency, this design utilizes a hybrid feedback feed-forward loop topology with SAR quantizer, feed-forward compensated amplifiers, and push-pull DACs. Further power efficiency is gained by performing excess-loop-delay compensation (ELDC) using the SAR quantizer SC-DAC, which reduces power overhead from ELDC to a negligible level. A 94 dB SFDR is achieved through feedback-DAC calibration. The 0.066 mm² design is fabricated in 28 nm CMOS and achieves FoMs of 36.4 fJ/step and 175.9 dB.