A new GaAs monolithic switch IC that can be operated with a single positive control voltage is developed. The implemented IC is provided two different biasing configurations with the switching FETs. Each FET can be biased independently by large capacitors fabricated employing the BST (Barium Strontium Titanate) technology. The fabricated SPDT (Single-Pole-Double-Throw) swicth IC shows insertion loss less than 1.0 dB and isolation over 25 dB in the frequency range of 0.1 GHz to 1.9 GHz with a single control voltage of 3 V.

A novel method to obtain a compact plastic package with higher isolation by providing subsidiary inner ground leads between outer leads is proposed and demonstrated. The effect of the subsidiary ground leads is investigated by using a 3-dimensional electromagnetic field simulation and measuring the fabricated packages. Newly designed package with subsidiary ground leads achieves higher isolation by more than 10 dB at 3 GHz as compared to a conventional package. This package is applied to GaAs SPDT switch IC's. Isolation of the switch IC's is improved by 5 dB at 3 GHz by the subsidiary inner ground leads. The isolation characteristics are discussed based on the equivalent circuit extracted from the simulation results.