An Ultra-Broad-Band Bridge-Type MMIC Switch Operating up to Millimeter-Wave Bands

Nobuaki IMAI

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E86-A    No.2    pp.268-272
Publication Date: 2003/02/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
millimeter-wave,  switch,  isolation,  bridge,  

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A novel ultra-broad-band bridge-type switch is proposed, which employs a bridge circuit consisting of four common-gate FETs. The isolation of conventional series- and shunt-type switches is limited by the switching device's performance, namely, the ON resistance (Ron) and the OFF capacitance (Coff). Some methods have been proposed to overcome this problem. However, most of them are band-limited. A feature of the newly-developed bridge-type switch is that its isolation characteristics do not depend on the Ron and Coff of the switching devices, but instead on the accuracy of the balancing bridge circuit, and thus ultra-broad-band characteristics can be obtained. The isolation for deviation of the bridge circuit elements and ON-state characteristics are calculated using a simple FET model. The fabricated bridge-type MMIC switch achieves less than 3.0 dB insertion loss and greater than 28 dB isolation in the broad frequency band up to 40 GHz.