A bi-stable electro-thermal RF switch for high power applications

This paper reports on the development of a bi-stable electro-thermal RF switch which can be operated with zero standby power (and bias) in either latched state. The device includes a bi-stable structure, which electrically shorts the input and output signal lines. Two electro-thermal actuators are used to switch it on and off. The entire structure is fabricated from 27 μm thick electroplated Cu, suspended 3 μm above a glass substrate. Typical actuation of the driving engine is performed by a 20 ms single pulse, corresponding to power and energy consumption of 33 mW and 662 μJ, respectively. Bursts of pulses of 0.1 ms width, used in sets of various durations, can reduce the total switching energy to <210 μJ. Measurements show that at 2.2 GHz, the device offers -0.5 dB insertion loss and -38 dB isolation, whereas at 3.5 GHz it offers -1 dB insertion loss and -30 dB isolation. Power handling capability tests for cold switching show that the device can be easily switched even after flowing >1 W RF power, suggesting that any micro-welding that may occur does not impede switching.