Broadband Millimeter-Wave GaAs Dual-Function Switching Attenuators With Low Insertion Loss and Large Attenuation Range

This paper presents millimeter-wave (mmW) wide-band dual-function switching attenuator chips based on gallium arsenide (GaAs) pseudomorphic high electron mobility transistor (pHEMT). The broadband attenuator chips integrate the function of absorption single-pole-single-throw (SPST) switch by using balanced architecture. By analyzing the effects of transistor size and parasitic couplings from bias lines on mmW attenuator chips, the attenuation range is further improved. Based on the 90-nm GaAs pHEMT process, a 26~80 GHz attenuator chip I and a 40~110 GHz attenuator chip II were designed and measured, with chip sizes of $1.65\ast 0.85$ mm2 and $1.30\ast 0.80$ mm2, respectively. In the operating frequency band, the measured insertion losses (IL) of chips I and II are less than 2.8 dB and 2.2 dB, respectively, with the return losses (RL) of better than 12.4 dB and 11.6 dB. At the center frequency, the measured attenuation ranges of Chip I and II are $1.4\sim 34.4$ dB and $1.1\sim 30.9$ dB, respectively, and the 1dB compressed input power ( $IP_{\mathrm {1dB}})$ of both chips are greater than 21 dBm. To the best of authors’ knowledge, this is the first wide-band mmW GaAs pHEMT attenuator chip integrated with absorption SPST switching function.