NEC's MMIC And MIC Activities For Microwave Telecommunications

A brief review of recent MMlC and MIC activities for telecommunications by NEC Corp. will be given: voltage controlled oscillators, power amplifiers, prescalers and a modulator are specific to this application. These MMICs and MICs are commercially available equipment, riot in the stage of research . INTRODUCTION MMICs and MICs play an important role in microwave and millimeter-wave telecommunication equipment because of advantages like high reliability and small size. Their characteristic of low cost is particularly important when they are used in big quantities like for very small aperture terminal (VSAT) satellite communication systems, personal communication network (PCN) systems, mobile telephone systems etc. In this paper we will describe some kinds of MMICs and MICs that are used in our microwave and millimeter-wave telecommunication equipment. v c o s Fig.1 shows a schematic diagr'am of the LO OSC that is used in NEC's VSA.T out door units (ODU). The VCO is stabilized by an analog phase-locked loop using a voltage controlled crystal osciriator (VCXO) and the VCXO is stabilized by a digital phase-locked loop using an oven controlled crystal oscillator (OCXO). In this subsystem the VCO and the sampling phase detector (SPD) are MIC modules. We have developed a 15.8GHz, +12dBm feedback-type VCO stabilized by a dielectric resonator for this application[']. A schematic diagram of the VCO is shown in Fig 3. NEC's 0 . 5 ~ m-gate-leingth GaAs MESFET, NEC's GaAs variictor diode and a dielectric resonator are constructed on a dielectric substrate (11.6" X 7.6" X O.635mm, E ,=9.8). Fig.4 and fig.5 show the: measured modulation sensitivity and temperature dependence respectively. We realized approximately 1.8h4HzJV modulation a 0.2dBpp output ]power level fluctuation an 1 .gpipm/"C frequency stability with a 0.4dBpp /-4Q°C---+80c output power level fli uation. Similar characteristics are achieved in a reflection-type \/CO whose schematic agmn is shown in fig.6.