W-band UWB pulse compression radar CMOS front-end

Abstract

With very large bandwidth availability and high resolution characteristics at millimeter-wave (mm-wave), the developments of short range radars (SRR) at 79 GHz are thought to open up new horizon of automotive sensor industrial markets. The 79 GHz band with -3 dBm of the highly specified power spectral density (PSD) can also obtain a high signal-to-noise ratio (SNR) and extend the maximum detection range. On the basis of these charac-teristics, silicon based 79 GHz radar front-ends adopted a phase modulated (PM) scheme has been progress in implementing compact and simple mm-wave radar systems on a die. However, the recent works have limitations on integrating RF blocks using frequency mul-tipliers without a voltage controlled oscillator (VCO) to mitigate the burden of a VCO hav-ing a wide tuning range and a low phase noise characteristic. At first, a fully-integrated W-band 4 GHz bandwidth (BW) pseudo-noise (PN)-coded pulse compression radar transmitter in a CMOS technology is presented. The PN-coded pulse compression scheme is adopted to obtain high spectral density and to lower the TX leakage using a 63 bit PN code generator based on linear feedback shift registers (LFSRs). We propose a sub-harmonic pumped pulse former and a pulsed PA for high TX efficiency with the suppression of LO/2LO leakage. A frequency synthesizer including a frequency divider chain generates a sub-harmonic LO signal as well as a 5 GHz digital clock. Digital blocks with the PN-code generator are synchronized with the clock signal, which makes all pulses start with the same phase. The proposed transmitter achieves 14.5 dBm maximum output power with the tuning range of 75 ~ 81.3 GHz, and the phase noise is -95.2 dBc/Hz at a 1-MHz offset in the range of LO frequencies. In pulse mode, it generates a 4 GHz BW RF pulse signal, which corresponds to a range resolution of 7.5 cm, and the average dc power dissipation is 160 mW. Finally, the first fully-integration of the ultra-wideband (UWB) W-band pulse compres-sion radar transceiver CMOS front-end is realized based on the designed transmitter. The transceiver achieves 14.5 dBm peak output power in the range of 75 ~ 81 GHz and a 7.5-GHz BW RF pulse, and is capable of measuring two targets 7-cm apart. The UWB radar module is implemented using a transmission line to waveguide transition. The implemented radar module can detect the target at distances of under 30 m.