Noise analysis of replica driving technique and its verification to 12‐bit 200 MS/s pipelined ADC

Abstract

This study demonstrates the noise analysis of a replica driving MDAC architecture, which is verified by implementing a 12-bit 200 MS/s replica driving pipelined analogue-to-digital converter (ADC). Based on the noise design strategy with the target effective number of bits = 10.5-bit, the overall dynamic performance degradation by KT/C noise and thermal noise by an amplifier is alleviated by removing the front-end sample-and-hold (S/H) circuit, and the transconductance (g m) of the inner source follower is maximised by increasing the current and threshold voltage (V T) reduction. Replica input sampling networks are designed for the first-stage sub-ADC and the first-stage MDAC with different aspect ratios to minimise the sampling skew for the S/H-less architecture. A prototype 12-bit 200 MS/s ADC is fabricated in a 65 nm complementary metal oxide semiconductor. The measured spurious-free dynamic range (SFDR) and signal-to-noise distortion ratio (SNDR) at a 1.0 MHz input signal is 82.6 and 65.6 dB, respectively, and SFDR and SNDR at the Nyquist (=99.0 MHz) input are 77.3 and 58.6 dB, respectively. The ADC core and the reference driver consume 53.9 and 13.2 mW, respectively, at a 1.2 V supply voltage.