A new mm-wave IC, constructed by flip-chip bonded heterojunction transistors and microstrip lines formed on Si substrate, has been proposed and demonstrated by using MBB (micro bump boding) technology. Millimeter-wave characteristics of the MBB region has been estimated by electro-magnetic field analysis. Good agreements between calculated and measured characteristics of this new IC (named MFIC: millimeter-wave flip-chip IC) have been obtained up to 60 GHz band. Several MFIC amplifiers with their designed performances have been successfully fabricated.

A high power amplifier module has been developed for large cell base station in digital cordless system. For PHS application, this module exhibited Pout of 38 dBm with low ACP of -72 dBc (at 600 kHz offset point) and a power gain of 33 dB at a supply voltage of 9 V and a frequency range of 1890-1923 MHz. In order to realize this ultra low distortion performance, power FETs have been designed as considering high breakdown voltage and thermal stability. Power divider/combiner circuits, which have the advantages of low transmission loss and a function of controlling second harmonic, have been introduced. Moreover, a novel module package with features of low cost and good processing precision has been proposed.

A small-sized three-stage GaAs power module has been developed for portable digital radios using M-16QAM modulation. This module has exhibited typical P1dB of 10 W with PAE of 48% and a power gain of 35 dB at a low supply voltage of 6.5 V in 1.453-1.477 GHz band. The volume of the module is only 1.5 cc, which is one of the smallest value in 10 W class modules ever reported. In order to realize the reduced size and the high power performances simultaneously, the module has employed new power divider/combiner circuits with significant features of the reduced occupation area, the improved isolation properties and the function of second-harmonic control.