A New 5–13 GHz Slow-Wave SPDT Switch With Reverse-Saturated SiGe HBTs

This letter describes the analysis, design, and measured results of a fully integrated single-pole double-throw (SPDT) switch developed in 0.25-μm silicon- germanium (SiGe) BiCMOS process technology, which features SiGe HBTs with peak fT/fmax of 110/180 GHz. The switch is designed based on a shunt-shunt topology with a combination of various design and layout optimization approaches to improve the insertion loss (IL), isolation, and power handling capability. The designed switch including the applied techniques results in a measured IL of 2.3 dB and isolation of 32 dB at 8 GHz. The switch is able to attain a state-of-the-art input referred 1-dB compression point (IP1 dB) up to 30 dBm while drawing a current of 3 mA from a 6 V supply. The die has an area of only 775 μm × 820 μm. To the author's knowledge, the presented work is the first SPDT switch ever reported, that incorporates slow-wave transmission lines and reverse-saturated heterojunction bipolar transistors at the specified frequency range.

I. Introduction

The next generation radar and communication systems consist of thousands of radiating elements spaced at the fractional wavelength of operating frequency to electronically steer the beam, and they are assembled using low cost, fully integrated transmit/receive (T/R) modules to reduce both deployment and operational expenses [1], [2]. Using a switch allows the T/R module to share a single antenna and reduces the occupied area. Moreover, since the switch is placed before any amplification stage, its insertion loss (IL) is directly added to the receiver noise figure, where the isolation of the switch also has a significance to prevent self-interference. Additionally, in the transmit mode the switch has to be capable of handling the large signal introduced by the power amplifier (PA). Therefore, high-quality switches are the key elements for any time-division duplexing T/R system for their compactness and performance.