35 GHz InGaAs HEMT MMIC downconverter

The design and development of a 35 GHz HEMT (high electron mobility transistor) MMIC (monolithic microwave integrated circuit) downconverter are reported. This completely monolithic chip consists of a balanced two-stage low-noise amplifier (LNA) cascaded with a singly balanced (HEMT compatible) diode mixer. Conversion gain of 5 dB over a 20 to 100 MHz IF (intermediate frequency) output with an RF frequency of 35 GHz and an LO (local oscillator) frequency=RF+IF has been measured. In addition to the downconverter macrocell, the LNA and mixer designs were fabricated as individual microcells. The LNA has demonstrated state-of-the-art performance: the measured noise figure from 34 to 40 GHz is less than 2.8 dB. Associated gain is 14.0+/-0.4 dB over a 30 to 40 GHz bandwidth. Input and output voltage standing wave ratio is better than 1.2:1. The singly balanced mixer exhibited conversion loss of less than 5 dB.<
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