Semiconductor switches and switching circuits for microwave

Abstract

The purpose of the present invention is to provide a small-sized switch attaining high isolation of not less than 80 dB, maintaining low insertion loss also in high frequencies not less than 60 GHz. A semiconductor switch according to the present invention utilizes FETs a gate electrode, a source electrode, and a drain electrode of each of which are formed on a semiconductor. The source electrode and the drain electrode are connected with the earth as well as are disposed in parallel to each other, and the gate electrode is formed between the source electrode and the drain electrode, and both the ends of the gate electrode are connected to the first input-output terminal 1 and the second input-output terminal.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to semiconductor switches, and in particular to semiconductor switches for microwave as well as millimeter wave bands using a transmission line comprising a dielectric substance substrate and metal conductors, and diodes or field effect transistors (FETs) showing distributed parameter effect. [0003] 2. Description of the Prior Art [0004] As a semiconductor switching circuit which is contemplated for use in microwave as well as millimeter wave bands, in particular with high frequencies not less than 60 GHz, various kinds of circuits have been proposed and manufactured for trial. [0005] Single-pole 3-throw (SP3T) switches for the 77 GHz band (hereinafter to be referred to as Conventional example 1) were reported by M. Case et al. in “1997 MTT-S IMS Digest pp. 1047-1050” and can be nominated as an example of conventional switches. [0006] An SP3T switch of Conventional example 1 comprises configur...

AI Technical Summary

Benefits of technology

"The present invention provides semiconductor switches and switching circuits that can solve problems of high loss and low isolation in conventional switches. The switches and circuits have the ability to function as a coplanar line without loss in the ON state and with loss in the OFF state. The isolation of the switches gradually increases on frequency, and the resistance value determining isolation depends on the distance between the gate and the source or drain. The switches are compact and have lower loss and higher isolation compared to conventional examples."

Problems solved by technology

As a result, a signal pass where a diode is biased in the reverse direction allows signals to travel transparently, but on the other hand, an increase in frequency will result in an increase in loss due to reflection.

On the contrary, FETs as well as PIN diodes, etc., normally have variation of forming process to a certain extent, but for example, due to this variation, the value of capacitance C could deviate from the design, and as a result the resonance frequency will deviate from the design as well, and resonance will not be available at a desired frequency, which, as a consequence, will give rise to reduction of yield.

However, not only in switching circuits of the above-described Conventional example 1 as well as Conventional example 2 without doubt, but also in switching circuit of Conventional example 3 it was practically difficult to maintain low insertion loss and realize high isolation in a wide band as a comparatively compact type.

As understandable from these features, in microwave or millimeter wave band switching circuits there was a problem that it was difficult for the prior art to realize high isolation of not less than 80 dB covering a wide band width with a comparatively small type configuration, while maintaining low insertion loss.

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