A prototype down‐converting mixer MMIC based on planar Schottky diodes and a production version based on HEMT diodes are reported. Measurements with a 1–2‐GHz i.f. indicate conversion losses of 8–11 and 10–14 dB, respectively, and image rejections > 20 dB. A HEMT‐based mixer‐amplifier MMIC with conversion gain of 3–8 dB and image rejection > 18 dB is also reported. Simulations agree well with these measurements. Image rejection is produced by an on‐chip i.f. coupler. This is the first report, to the authors' knowledge, of fully monolithic, image‐reject downconverters of this type. © 1995 John Wiley & Sons, Inc.
- Image reject
- wireless communication