High LO-to-RF isolation 94 GHz coplanar monolithic down-converter for FMCW radar sensor applications

Sung Woon Moon, Jung Hun Oh, Byoung Chul Jun, Sam Dong Kim

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

This paper presents a 94 GHz monolithic down-converter with low conversion loss and high local oscillator (LO)-to-RF isolation using the 0.1 μm T-gate metamorphic high electron-mobility transistor (MHEMT) technology. The down-converter consists of a one-stage amplifier and a single-balanced mixer based on the high-directivity tandem coupler structure using the air-bridge crossovers, thereby amplifying the RF signals and maximizing the LO-to-RF isolation by using an inherent S12 isolation characteristic of the amplifier and good phase balance of the tandem coupler. The fabricated one-stage amplifier using a 30 μm × 2 MHEMT shows a small signal gain of 7 dB at 94 GHz. The single-balanced mixer comprising two 20 μm × 2 MHEMT Schottky diodes and the tandem coupler with an additional λ/4-length line exhibits the conversion loss less than 7.8 dB and the LO-to-RF isolation higher than 30 dB in a RF frequency range of 91-96 GHz. Two circuits designed both for a 50 Ω impedance system are integrated into the down-converter of a 2.6 × 2.5 mm2 chip size, and it shows a low conversion loss of ∼1 dB at 94 GHz and excellent LO-to-RF isolation above 40 dB in a frequency range of 90-100 GHz. This is the best isolation among the W-band monolithic down-converters reported to date.

Original languageEnglish
Pages (from-to)395-400
Number of pages6
JournalCurrent Applied Physics
Volume10
Issue number2
DOIs
StatePublished - Mar 2010

Keywords

  • 94 GHz
  • Coplanar MMIC
  • Down-converter
  • High isolation
  • Metamorphic HEMT

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