Bitstream radar waveforms for generic single-chip radar. Issue 6 (22nd August 2017)

• Record Type: Journal Article
• Authors: Bjørndal, Øystein; Hamran, Svein-Erik; Lande, Tor Sverre
• Editors: Nightingale, Steve; Abunjaileh, Alaa; Danoon, Laith
• Is Part Of: International journal of microwave and wireless technologies. Volume 9:Issue 6(2017)
• Page Start: 1325
• Page End: 1337
• Publication Date: 2017-08-22
• Subjects: Radar architecture and systems, -- Si-based devices and IC technologies; Wireless communication systems -- Periodicals; Microwave circuits -- Periodicals; Radio frequency -- Periodicals; 621.381305
• DOI: 10.1017/S1759078717000782
• Languages: English
• ISSNs: 1759-0787

Abstract

Abstract : Bitstreams, square wave digital signals, enable flexible radar implementations in modern digital technology. By using bitstreams in place of analog sinusoidal waveforms, we can realize continuous-wave (CW), stepped-frequency CW, frequency-modulated CW, or even pseudo random noise-sequence and pulsed radars, all with a single bit of amplitude resolution. The building blocks are a programable waveform generator, a sweep threshold quantizer, digital delay, and a digital XOR gate as a mixer. This gives us a novel, almost fully digital (requiring only a comparator) system, as previously proposed and which is extended here. The flexibility of the transmitter allows for easy switching between waveforms and the bitstream signal can be processed with single-bit digital gates. Single-bit signals allows for exploration of novel continuous time non-clocked digital implementations to maximize speed and energy efficiency. Mixing frequencies with a digital XOR gate creates harmonics, which are explored for multiple solutions utilizing digital delay. Analytical as well as simulation results are presented. Initial measurements from a 90 nm CMOS chip is provided for the transmitter and the full system, proving the feasibility of a digital future in radar.