Equivalent-Time Direct-Sampling Impulse-Radio Radar With Rotatable Cyclic Vernier Digital-to-Time Converter for Wireless Sensor Network Localization

This paper presents a rotatable cyclic Vernier digital-to-time converter (DTC) with 1.8 ps timing resolution on an 80 ns time scale. The proposed DTC features high timing resolution, and can be utilized in beam-steering arrays, which is infeasible for ordinary Vernier DTCs. The proposed DTC was implemented within a passive time-equivalent direct-sampling ultra-wideband impulse-radio radar system and was fabricated in 65 nm CMOS technology. This radar system is capable of quantizing direct-sampled impulse waveforms to provide full degrees of freedom for backend digital signal processing. The measured differential nonlinearity/integral nonlinearity of the DTC was +4.6/-3 and 12.4/-9.4 where the LSB was 1.8 ps, and the total power consumption was 133 mW. Also, a new method for localization between wireless sensor nodes of equivalent-time direct-sampling radar is presented in this paper; this method can theoretically achieve resolution as high as that of regular radar.

I. Introduction

Every year, CMOS technology continues to follow Moore’s law, and continues to achieve ever-higher levels of integration [1]. Recent advances in CMOS technology have enabled designers to integrate radar systems at the chip level. The fully integrated radars are superior to their discrete counterparts in cost and size. Traditional radars require a large quantity of discrete components integrated on board level, which make them bulky and costly. On the other hand, the fully integrated radars lower the radar’s size and cost on integration. Moreover, their low profiles make them attractive and competitive solutions for numerous applications, including vehicle collision avoidance systems [2]–[4] and biomedical signal sensing instruments [5]–[8].