An efficient high-resolution 11-bit noise-shaping multipath gated ring oscillator TDC

An 11-bit, 50-Msps time-to-digital converter (TDC) using a multipath gated ring oscillator (GRO) with 6 ps of delay per stage achieves low power (2.2 to 21 mW) and small area of 160times260 mum in 0.13 mum CMOS. The structure also achieves first order noise shaping of the GRO quantization and mismatch noise; the resulting TDC error integrates to <100 fs (rms) in a 1 MHz bandwidth to achieve dynamic range of over 90 dB with no calibration required.