A 38-GHz demodulator with high image rejection in 65 nm-CMOS process

Tian Wei Huang*, Yi Cheng Huang, Chen Chien, Kun Chan Chiang, Jeng Han Tsai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


A high image rejection 38 GHz demodulator in TSMC 65-nm CMOS process is presented. To achieve better than -40 dBc image rejection ratio (IRR), a low I/Q mismatch 45° LO power splitter of sub-harmonic mixer is proposed. In this design, the 45° LO power splitter is composed of a Wilkinson divider, a series delay line with electrical length of 45° on one side of the divider, and a shunt 90° transmission line on the other side. This configuration is attractive because of its design simplicity and easy fabrication. Compared with the conventional techniques that utilize capacitors and inductors instead of the shunt 90° transmission line, the proposed LO power splitter can alleviate the issue of process variation. The demodulator demonstrates an IRR lower than -40 dBc from 37.5 to 41.5 GHz. In addition, conversion gain is 1.3 ± 0.9 dB from 33 to 41 GHz with 6 dBm LO power. The total direct current power consumption is 78 mW from 1.0 V supply voltage. At the modulation scheme of 4096-QAM, the proposed demodulator demonstrates 1.7% (-35.1 dB) error vector magnitude (EVM), which is very close to the EVM measurement floor 1.6% (-36 dB) of our millimeter-wave signal analyzer.

Original languageEnglish
Pages (from-to)1327-1333
Number of pages7
JournalInternational Journal of Microwave and Wireless Technologies
Issue number8
Publication statusPublished - 2023 Oct 21


  • CMOS
  • Power amplifier

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


Dive into the research topics of 'A 38-GHz demodulator with high image rejection in 65 nm-CMOS process'. Together they form a unique fingerprint.

Cite this