A Chebyshev-response step-impedance phase-inverter rat-race coupler directly on Lossy silicon substrate and its Gilbert mixer application

Hung Ju Wei*, Chin-Chun Meng, Sheng Wen Yu, Chia Hung Chang

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

This paper focuses on the analysis and the design methodology of the step-impedance phase-inverter rat-race coupler on a silicon-based process. The issues of impedance limitation and bandwidth are discussed in detail. Our proposed concept utilizes a high silicon dielectric constant, phase-inverter structure, step-impedance technique, and Chebyshev response to make the rat-race coupler more compact (∼ 64% reduction) and highly balanced over a wide operating bandwidth. Moreover, the inter-digital coplanar stripline used in the step-impedance section effectively reduces the characteristic impedance of the transmission line for large size shrinkage and insertion-loss reduction. The demonstrated step-impedance rat-race coupler directly on silicon substrate has 6-∼ 7-dB insertion loss from 5 to 15 GHz and small variations in amplitude/phase balance. Compared with our previous work, the proposed rat-race coupler achieves a 3-dB improvement in the insertion loss. Thus, a 0.13-μ m CMOS Gilbert down-converter with a miniature phase-inverter rat-race coupler at the RF path for wideband single-to-differential signal conversion achieves a noise figure of 16 dB.

Original languageEnglish
Article number5716702
Pages (from-to)882-893
Number of pages12
JournalIEEE Transactions on Microwave Theory and Techniques
Volume59
Issue number4 PART 1
DOIs
StatePublished - 1 Apr 2011

Keywords

  • Broadband
  • Chebyshev response
  • CMOS
  • coplanar stripline (CPS)
  • distortionless
  • down-converter
  • phase inverter
  • rat-race coupler
  • step impedance

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