Effects and contrasts of silicon-on-insulator floating-body and body-contacted field-effect transistors to the design of high-performance antenna switches

A theoretical analysis and contrast of silicon-on-insulator (SOI) floating-body (FB) and body-contacted (BC) metal-oxide-semiconductor field-effect transistors (FETs) including insertion loss (IL), isolation, power handling capability as well as harmonics for radio frequency switches applications, are firstly developed in detail. From the presented investigation, lower IL and smaller chip size can be obtained using FB FETs, while the BC devices are beneficial to isolation and harmonics improvement. As an experimental vehicle for the presented analysis, the high-power single-pole eight-throw (SP8T) antenna switches for multi-mode multi-band applications, are fabricated in a partially depleted 0.18 mu m SOI process based on FB and BC FETs, respectively. At 1.9 GHz, the tested IL, TR x 1 to TR x 3 isolation, and P-0.1 dB of the FB and BC SP8T switches are approximately 0.53/0.65 dB, 27.6/29.3 dB and 38.0/38.4 dBm. For the two cases, the second and third harmonics are -70.6/-75.5 and -60.4/-79.9 dBc, respectively, with a +33 dBm input power at 1.9 GHz. The experimental results strongly support the analysis that the FB FET is a preferred device in low loss or low throw-count switching design while the BC FET is a better selection in the applications that demand high power and low harmonic.