Steven C. Sprinkle

Design of a low VSWR harmonics, low loss SP6T switch for GSM/Edge applications.

In this paper the design and measurement of a high performance SP6T GaAs pHEMT switch for Quad-Band GSM/EDGE Front-Ends are discussed. The design uses a novel approach to reduce the generated harmonic levels at 3 V supply, 35 dBm drive and antenna VSWR of 5:1 down to -40 dBm, the lowest levels for the multi-mode multi-throw switches reported to date. Besides low harmonic performance, low TX insertion loss of below 0.5 dB at 2 GHz and RX insertion loss of below 1 dB at 2 GHz is achieved.

Optimum Matching Technique for the Switch Design

The theoretical background and hardware implementation of optimal matching filters designed to minimize harmonic generation by RF switches and provide harmonic filtering of the PA generated harmonics is presented. The switch with the optimally matched filters shows 5-7 dB improvements in harmonics generated under high VSWR, leading to better than -39dBm harmonics at 35/33 dBm for all phases of VSWR=5:1 for low/high band GSM applications. This technique leads to a fully integrated solution offering both improved harmonics performance and reduced size.