A Direct-Sampling Pulsed Time-of-Flight Radar With Frequency-Defined Vernier Digital-to-Time Converter in 65 nm CMOS

This paper presents a direct-sampling pulsed radar with a high-resolution digital-to-time converter (DTC) for estimating the time of flight (TOF), which is to identify the distance between a target and radar. The implemented direct-sampling radar can reconstruct the scanning waveforms in digital domain. The link budget of the radar transceivers is analyzed for the overall scanning range. The scanning range of the radar is dependent on the TOF between radar transmitter and receiver. The range resolution of the pulsed TOF radar is determined by DTC. With the help of exquisite DTC, a high resolution radar can be achieved. The vernier concept has been adopted to achieve an accurate timing resolution design in the DTC. The vernier time steps are defined by the oscillating frequency of the phase-locked loops (PLL), and therefore the DTC with a high resolution in the order of picosecond and with high immunity to PVT variation was developed and demonstrated. The proposed radar was fabricated using 65 nm CMOS technology and occupies a chip area of 2 mm ², consumes 88.4 mW of DC power. The receiver has a 10 GHz instantaneous front-end bandwidth for capturing all scattering reflected waveforms and a 666 GS/s equivalent sampling rate for recording all received signals for subsequent digital signal processing (DSP) analysis.

I. Introduction

Currently, radars are widely used, from the speed measuring radar and biomedical image sensors encountered in daily life to the military radar pertaining to national security. With the rapid development of CMOS technology, device density has increased, device performance has improved, and cost has decreased considerably [1]. Thus, fully integrated radar sensors have been developed and become considerably cheaper, so that the general public can afford them.