A 35-GHz TX and RX Front End With High TX Output Power for Ka-Band FMCW Phased-Array Radar Transceivers in CMOS Technology

A 35-GHz transmitter (TX) and receiver (RX) front end in CMOS technology for Ka-band frequency-modulated continuous wave (FMCW) phased-array radar transceivers are presented in this article. While typical FMCW phased-array radar transceivers use RF-path phase-shifting scheme for both TX and RX front ends, the Ka-band TX and RX front ends presented in this article are designed for TX-analog and RX-digital beamforming phased-array radar system. The link budget for the Ka-band phased-array radar transceiver is investigated. In order to improve the TX output power level, a power amplifier (PA) with a four-way power splitter/combiner is introduced. The detailed analyses and design considerations of the PA are investigated. The proposed TX and RX front ends are implemented and fabricated in a 1P9M 65-nm CMOS technology. The measured TX output power is 19 dBm. To the best of authors' knowledge, it is the highest output power FMCW module at the Ka-band using CMOS technology reported so far. The RX achieves a conversion gain of 29.6 dB. The TX occupies 1.42 mm² and consumes 588 mW. The RX occupies 0.59 mm² and consumes 72 mW.

I. Introduction

The use of Ka-band for remote sensing introduces more and more opportunities in industrial and civil security applications since there is a low atmospheric absorption loss around 35 GHz. Radar sensors operating in this band are expected to be realized in a CMOS technology for low-cost and high-integration solution [1]. As for the modulation scheme, linear frequency-modulated continuous wave (FMCW) radar is a popular choice for energy-efficient application at the Ka-band due to its constant envelope modulation, which enables the adoption of linear amplifier with saturation output.