A Continuous Time Multi-Bit ADC Using Time Domain Quantizer and Feedback Element

摘要

A third-order CT $Delta Sigma$ ADC that replaces the multi-bit quantizer and feedback DAC by a pulsewidth modulation (PWM) generator and time-to-digital converter (TDC) is implemented in 65 nm CMOS technology. The TDC provides a 50-level binary output code and a time-quantized feedback pulse to the modulator. It is shown that the TDC can achieve 11 bit linearity in time steps without calibration or dynamic element matching. The modulator achieves 68 dB DR in 20 MHz BW, consumes 10.5$~$mW and occupies 0.15 ${hbox {mm}}^{2}$.