Abstract

Several MMIC downconverters have been developed for use in experimental 30/20 GHz Satellite Personal Communications Terminals. The non-linear PHEMT and diode models are described and the design and performance of the downconverters are discussed. The design and performance a 30 GHz single-balanced PHEMT diode upconverter is also reported. The 20/4 GHz downconverter has a conversion loss of 1.5 dB at 20 GHz while the 30/4 GHz version was found to have 3.0 dB loss at 30 GHz. Both mixers showed spurious suppression better than 40 dB and required 3.5 dBm of LO power. The DC-50 MHz/30 GHz single balanced PHEMT diode upconverter, using a miniature distributed 180° hybrid, was found to have 10 dB conversion loss between 10 and 50 MHz. The RF-LO isolation was 22 dB.