An X-Band Frequency-Modulated Continuous-Wave Radar Sensor System with a Single-Antenna Interface for Ranging Applications

Hao Chung Chou*, Yu Hsien Kao, Chun Chieh Peng, Yu-Jiu Wang, Ta Shun Chu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


In this paper, a highly integrated frequency-modulated continuous-wave (FMCW) radar system with a single-antenna interface for range sensing is proposed. In this paper, a circulator structure was developed and used in the radar system with the single-antenna interface. This structure capitalizes on frequency orthogonality to separate transmitted and received signals; thus, the isolation can be improved by using integrated filters to further suppress transmitter leakage. Without an additional back-end leakage cancellation mechanism and antenna tuner, the single-antenna FMCW radar system can be devised. The proposed system is composed of a radar transceiver, a frequency synthesizer, an analog signal processor, and an AD converter; the system is fabricated using a 65-nm CMOS technology, occupies a chip area of 1.9 mm2, and consumes 147-mW dc power under a 1.2-V power supply. The implemented front-end circuit can provide an output power of 10.5 dBm with power efficiency of 30%, over 1-GHz impedance matching, an insertion loss of 2 dB, a maximum noise figure of 16.8 dB (including the following IF amplifier), P1dB of 2 dBm, and IIP3 of 7 dBm. A wireless measurement process proved that the system can provide a 37-cm range resolution over a 50-m range for a 20 × 20 cm2 copper plate. Finally, an FMCW radar front-end board and a digital signal processing board were implemented for data analysis, thus completing the FMCW radar sensor unit. The proposed system can be utilized for multiple applications including 1-D object tracking, 2-D localization, and 3-D object tracking.

Original languageEnglish
Article number8428439
Pages (from-to)4216-4231
Number of pages16
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number9
StatePublished - 1 Sep 2018


  • Circulator
  • CMOS
  • CMOS radar
  • duplexer
  • frequency-modulated continuous-wave (FMCW)
  • quasi-circulator
  • sensor


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