A 0.22 ps(rms) Integrated Noise 15 MHz Bandwidth Fourth-Order Delta Sigma Time-to-Digital Converter Using Time-Domain Error-Feedback Filter

Abstract

In this paper, a fourth-order Delta Sigma time-to-digital converter (TDC) is proposed to achieve high resolution and wide signal bandwidth. The proposed TDC is based on a 1-3 multi-stage-noise-shaping (MASH) architecture, where the first-stage is a gated-ring oscillator based TDC (GRO-TDC) and the second-stage is a single-loop third-order Delta Sigma TDC based on a time-domain error-feedback filter using time registers, time adders and time amplifiers. Implemented in 65 nm CMOS process, the prototype TDC achieves 0.22 ps(rms) of integrated noise within 15 MHz signal bandwidth at 300 MS/s while consuming lower than 6.24 mW. The proposed TDC occupies an active die area of only 0.03 mm(2).