A 60-GHz-band monolithic HEMT amplifier for which BCB thin film layers are adopted on GaAs substrate has been developed. The MMIC utilized a thin film microstrip line for the bias circuit and a coplanar waveguide for the RF circuit. The coplanar waveguide has the advantage of low loss, whereas the thin film microstrip line has the advantage of small size. Two different types of transmission lines were selected to coexist in the monolithic amplifier. As a result, the MMIC achieved high gain over a wider frequency range at a small size. This MMIC had a gain of over 15 dB in a frequency bandwidth of 11 GHz. In particular, the high-frequency characteristics of the transmission lines and the HEMTs were evaluated in detail for the conventional MMIC structure and the new MMIC structure. It was confirmed that this newly developed MMIC using BCB thin film layers is attractive for millimeter-wave applications.

A miniature transceiver, including highly integrated MMIC front-end, for 1.9 GHz band personal handy phone system(PHS) has been developed. The terminal, adopting direct conversion transmitter and receiver technology, consists of four high-density RF circuit modules and a digital signal processing LSI with 2.7 V power supply. The four functional modules are a power amplifier, a transmitter,a receiver, and a frequency synthesizer. Each functional module includes one IC chip and passive LCR components connected with solder bumps on module substrate. The experimental miniature PHS handset has been fabricated to verify the design concepts of the miniature transceiver. The total volume of the developed PHS terminal is 60cc, including the 12cc front-end which comprises the four RF functional circuit modules. The air interface connection with the PHS base station simulator has been confirmed.