A low insertion loss switch using ordering InGaP/AlGaAs/InGaAs pHEMT technology

Abstract

A low insertion loss (LIL) switch for GSM and WLAN applications was demonstrated by using 0.5 μm gate length InGaP/AlGaAs/InGaAs pHEMT technology. In order to improve the circuit reliability during a long-term high power operation, an ordering InGaP Schottky layer was applied in this study. The ordering type InGaP Schottky layer also provides an extreme lower Δ E c (<0.1 eV) as compared with AlGaAs ones. This characteristic is helpful to improve contact resistance and insertion loss of the switch. The fabricated LIL switch integrated circuit (IC) achieved a low insertion loss of 0.18 dB at 0.9 GHz. This InGaP/AlGaAs/InGaAs pHEMT has demonstrated an output power density of 284 mW/mm with drain-to-source voltage ( V ds) equal to 3 V at 2 GHz. Beside, both on-resistance ( R on) and steady-state drain current ( I dss) of 10 FET switches with gate width ( W g) equal to 2 mm maintained a stable performance during 3000 h reliability evaluation, achieving a variation less than 5%. Therefore, this novel design exhibited a high potential in LIL switches and PA MMIC design for GSM and WLAN applications.