A 20MHz Bandwidth Band-Pass Noise-Shaping SAR ADC With OPAMP Sharing Switched-Capacitor Filter

This paper proposes a 20MHz bandwidth time-interleaved based band-pass noise shaping SAR, which is especially suitable for high frequency ultrasound imaging systems. A high power efficiency op amp sharing switched-capacitor filter is employed and the total amount of capacitance is thus reduced by about 4 times compared with fully-passive noise shaping SAR ADCs. The proposed SAR ADC is designed and simulated in a 0.18um BCD high voltage process as part of a highly integrated ultrasound transceiver system. At 80MS/s sampling rate, the OSR is set to 2. The simulation results show that the ADC achieves an ENOB of 11bits with a 10-b ADC architecture.