A Pseudo-Pseudo-Differential ADC Achieving 105dB SNDR in 10kHz Bandwidth Using Ring Amplifier Based Integrators

Abstract

This brief presents a high-resolution ADC which makes use of the pseudo-pseudo-differential noise filtering technique in an oversampling ADC architecture with ring amplifier based integrators. The pseudo-pseudo-differential noise filtering technique utilizes single-ended circuits while maintaining the even-order rejection found in fully-differential structures which alleviates, in the active analog blocks, the need for differential matching and circuit overhead such as common-mode feedback. Additionally, pseudo-pseudo-differential provides a cancellation of low frequency flicker noise without the need for traditional techniques such as auto-zero, correlated-double-sampling, or chopping and mitigates double-sampling thermal noise penalties by processing input signal twice. In this prototype, the flicker corner is maintained below 50Hz with measured ADC performance achieving a peak SNDR of 105.0dB and a dynamic range of 106.5dB while consuming 1.17mW from a 1.8V supply.