A compact 281-319 GHz low-power downconverter MMIC for superheterodyne communication receivers

This article presents a fully integrated first downconversionstage for a superheterodyne receiver for high data ratecommunication at 300 GHz. It comprises a frequency multiplierby-three, an active dual-gate downconverter, and an LNA. Thechip was fabricated in a 35-nm InGaAs-based metamorphic highelectron-mobility transistor technology. The downconverter wasdesigned to be used for different local oscillator (LO) frequenciesbetween 70 and 80 GHz and intermediate frequency (IF)frequencies from 65 to 95 GHz, to create multiple channels forreal-time full-duplex communication in the terahertz region. Itachieves a conversion gain of 14 dB without IF amplification and3-dB bandwidth of 25 GHz in the desired upper sideband from288to 313 GHz and an estimated NF of 6.6 dB. Without the LNA, theconversion gain of the circuit is −10 dB and it shows 3-dB bandwidthof 38 GHz in a frequency range from 281 to 319 GHz. Finally,the millimeter-wave monolithic integrated circuit (MMIC) willbe compared in detail to a similar state-of-the-art downconverterusing a resistive mixer and a necessary additional LO buffer stagein the same technology targeting the identical application. Whileexhibiting a better conversion gain and bandwidth and occupyingonly40%of chip area, the presented downconverter consumes70%less dc power than the MMIC with a resistive mixer.