A Q-band monolithic balance resistive HEMT mixer using CPW/slotline balun

A Q-band balanced, resistive high-electron-mobility-transistor (HEMT) mixer has been developed for integration in monolithic millimeter-wave receivers. The mixer consists of two AlGaAs/GaAs HEMTs, a coplanar-waveguide (CPW)-to-slotline local oscillator (LO) balun, and an active IF balun. CPWs are used to eliminate the backside or via-hole process step, which increases the circuit yield and shortens the processing time. The conversion loss of the mixer while downconverting a 42-46-GHz RF to a 2.3-3.2-GHz IF is between 4 and 8 dB using an LO drive of 14 dBm. A 17.5-dBm input two-tone third-order intermodulation intercept point is achieved with an LO drive of 10.5 dBm, while a 5.5-dBm input, 1-dB compression point can be achieved with an LO drive of 14 dBm. This is the first reported monolithic CPW resistive HEMT mixer operating at Q-band frequencies.<
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