A TD-ADC for IR-UWB Radars with Equivalent Sampling Technology and 8-GS/s Effective Sampling Rate

A high-speed time domain analog-to-digital converter (ADC) customized for impulse radio ultra-wideband (IR-UWB) radars is proposed in this brief. It adopts a power efficient architecture combining time domain implementation and equivalent sampling technology. The equivalent sampling rate is high up to 8 GS/s. Compared to time interleaved (TI) ADC, the proposed time domain ADC (TD-ADC) not only has less power consumption and silicon area, but also is free from complicated digital calibration. The prototype ADC was fabricated in a 65nm CMOS technology. The achieve area is 320 ${\mu }\text{m}\,\,\times $ 300 ${\mu }\text{m}$ . With the Nyquist middle frequency input of 1.376 GHz, the measured spurious free dynamic range (SFDR) and signal to noise and distortion ratio (SNDR) are over 57.6 dB and 43.0 dB, while the real time power consumption is only 8.2 mW. The figure of merit (FOM) is about 147 fJ/step.