A Technique for Correction of Parasitic Capacitance on Microwave ftMeasurements of MESFET and HEMT Devices

Milton Feng, C. L. Lau, C. Ito

Research output: Contribution to journalArticle


The current gain cutoff frequency, ft, has become a critical figure-of-merit for evaluating performance of MESFET and HEMT devices. The ft is related to a capacitance parameter, Ctot, through the equation ft= Gm/(2πCtot). This capacitance, however, includes a parasitic component primarily due to contact pad and device geometry as well as a parasitic component due to Rd, Rs and Rds. This paper describes a technique which determines this parasitic capacitance for FET-type devices. Consistently accurate corrections can then be made to reported ft values. Ion implanted InGaAs MESFET’s with 0.25 µ gate lengths have achieved 120 GHz ft before correction and 151 GHz f, after correction.

Original languageEnglish (US)
Pages (from-to)1880-1882
Number of pages3
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number11
StatePublished - Nov 1991


ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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