In this paper, the reason for the relatively high distortion level of conventional class-D audio amplifiers is discussed. It is pointed out that the classical approach is insufficient for high performance applications. Therefore the importance of the matching between modulation and demodulation is demonstrated by simulation. 1. THE CLASS-D-AUDIO AMPLIFIER The concept of class-D amplifiers was i...

In this paper, we compare two X-band highefficiency switched-mode amplifiers designed around two commercially available packaged MESFET’s, one having a four times larger gate periphery than the other. The amplifiers using the larger and smaller devices are designed to operate in classes E and F, respectively. The smaller device gives 685-mW output power with 7.4-dB gain and 64% overall efficien...

The market for millimeter-wave power amplifiers includes applications in military, commercial and consumer sectors. The armed forces use the devices in transmitters for the detection of small targets and target imaging, in radar equipment, communications and smart weapons systems. In the commercial sector the amplifiers are widely used in high-data-rate communication systems such as digital rad...

Gallium Nitride (GaN) HEMTs are the focus of intense research and development due to their potential for the realization of MMIC power amplifiers (PAs) with high gain and record levels of power delivery [1]. Much of the work in GaN HEMT development has been concentrated on performance demonstration on 2” SiC and Sapphire substrates. Multiple groups have demonstrated GaN HEMTs delivering record ...

This article is based on “Class-E High-Efficiency Power Amplifiers, from HF to Microwave,” Proceedings of the IEEE International Microwave Symposium, June 1998, Baltimore; and “ClassE Switching-Mode High-Efficiency Tuned RF Microwave Power Amplifier: Improved Design Equations,” Proceedings of the IEEE International Microwave Symposium, June 2000, Boston; both by Nat Sokal, © IEEE 1998, 2000.—Ed.

In this contribution, a set of robust GaN MMIC T/R switches and low-noise amplifiers, all based on the same GaN process, is presented. The target operating bandwidths are the X-band and the 2-18 GHz bandwidth. Several robustness tests on the fabricated MMICs demonstrate state-ofthe-art survivability to CW input power levels. The development of high-power amplifiers, robust low-noise amplifiers ...