GaAs HBT PIN diode attenuators and switches

An AlGaAs-GaAs heterojunction-bipolar-transistor (HBT) two-stage PIN diode attenuator from 1-10 GHz and an X-band one-pole, two-throw PIN diode switch are discussed. The two-stage PIN attenuator has over 50-dB dynamic range at 2 GHz and a maximum IP3 of 9 dBm. The minimum insertion loss is 1.7 dB per stage, and response is flat to 10 GHz. The X-band switch has an insertion loss of 0.82 dB and an off-isolation of 25 dB. The bandwidth is greater than 35% and the IP3 is greater than 34.5 dBm. Both of these circuits consist of PIN diodes constructed from the base-collector molecular-beam-epitaxy (MBE) layers of a baseline HBT process. The monolithic integration of PIN diode switch and attenuation functions in an HBT technology without additional process or MBE material growth is shown.<
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