A Signal Generator and Down-Conversion Mixer / TIA Unit for a 5.8-GHz FMCW Receiver in 65nm CMOS

Abstract

This paper presents a 5.8 GHz FMCW signal generator with a maximum bandwidth of 275 MHz along with a down-conversion mixer / TIA with a peak homodyne structure down-conversion gain of 13.5 dB and a maximum baseband BW of 150 MHz. The FMCW signal is achieved by a ramp generator signal applied to the varactor bank of a VCO tank. The VCO differential signals are injected into a non-overlapping 50% duty cycle square wave generator which provides the desired LO signals applied to a passive current mixer. The FMCW signal generator and down-conversion mixer / TIA unit is implemented with the size of $\boldsymbol{0.3}\mathbf{mm}\times \boldsymbol{1.5}\mathbf{mm}$ in 65 nm CMOS technology. The VCO RF output looped back to RF port of the mixer and the 400 KHz baseband signal at the output of the receiver unit is measured by a low frequency oscilloscope and FFT extraction.