An area-efficient differential input ADC with digital common mode rejection

This paper presents a differential input flash ADC with digital common mode rejection (DCMR) and dithered, noise shaped requantization used in a high-performance, single-poly CMOS ADC ΔΣ modulator IC. By avoiding the use of metal-metal capacitors, the DCMR flash ADC required 14% less area than a switched-capacitor implementation and avoided circuit implementation problems. Measurements and analysis show that the DCMR flash ADC rejects common mode noise without generating spurious tones. In the absence of common mode noise, its quantization noise power is equivalent to a conventional flash ADC