Development of high-functional MMIC
The space-saving benefits of MMIC technology lead to cost reductions and high functionality. This is why small circuits allow us to transmit information or power efficiently. Our research group has accomplished a high-functional small module using compound semiconductor MMIC technology. In the application of mobile communication or space communication, we built prototypes of active circuits and high-performance communication equipment including metamaterial of artificial medium (crystal) in the radio-wave region. Thus, we are expanding the applications of compound semiconductors.
There are two types of general amplifier circuits for communication equipment: high-power (HPA) and low-noise amplifiers (LNA). A global trend in the past 10 years is active fabrication-less circuit-module development. Foundry services that outsource trial production of devices and circuits to external companies are being introduced in the microwave field. Foundry services, however, cannot guarantee design methodology or fabricated IC performance. Without our research groupís own original high-precision design methodology and verification technology, it is impossible to create world-class MMIC. Fig. 1 shows our prototype MMIC HPA and LNA (almost the same size, about 2.5mm x 3.0mm) operating in Ku band (12GHz to 18GHz frequency band). In comparison with non-monolithic circuits, their performance is the equivalent or better, and their size and weight are roughly 1/100th or less. The HPA achieved approx. 400mW output power in this size, while the LNA achieved noise of 1.7dB (0.96dB@10GHz 113K) at 10 to 14GHz. These boast world-class performance.
We also produced a trial model of a frequency converter (mixer) using GaAs MMIC technology as a new, high-functional amplifier as shown in Fig. 2. This combines metamaterial to transmit the signal back with a distributed-type amplifier, which consolidates semiconductor amplifier circuitry in multiple layers. The upper part of the figure is the metamaterial transmission lines while the lower part is the multi-stage mixer with FET amplifying function. The device is built very compactly and has excellent coordination of both impedances. It works efficiently as both amplifier and mixer.