Cascaded single-stage distributed amplifier using DPHEMT devices for multioctave performance

Abstract

This paper describes a multioctave (2---18 GHz) distributed amplifier design using the concept of cascaded reactively terminated single-stage distributed amplifier (CRTSSDA) configuration for EW applications. The concept of CRTSSDA is demonstrated to provide broadband performance with high gain, reduced power consumption, circuit stability and superior power-added efficiency compared to conventional distributed amplifiers using the same number of active devices. The broadband amplifier employing three-CRTSSDA is designed and fabricated using three different DPHEMT devices in the three respective stages of the design to further enhance the amplifier's efficiency performance. The amplifier achieved an associated gain level above 26 dB with flatness of <± 0.5 dB, an average power-added efficiency in access of 27% at an output power of 25 dBm across 2---18 GHz with an efficiency peak of 30% at 12 GHz. The input and output VSWR of better than 2:1 was achieved. Furthermore, the CRTSSDA provides a cost-effective solution when compared to the conventional travelling wave amplifier as only half the number of active devices is used. Fabrication of the amplifier was carried out by using the conventional thin-film microwave integrated circuit technology. The CRTSSDA is also disposed to realization by monolithic circuit technology.