High-frequency time-domain measurement techniques for switch-mode amplifiers

Published in:
German Microwave Conf. (GeMIC 2008), Hamburg-Harburg, Germany, Mar. 10-12, pp. 18-23 (2008).
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Abstract:
This paper introduces two measurement techniques for time-domain characterization of switch-mode amplifiers, particularly for class-S and class-D with differential output. GaN HEMT MMICs are presented. They achieve PAEs of 84% and 87% at 5 and 9 W output power, respectively. Moreover a class- D amplifier is characterized. The measurement techniques are unique since one provides a differential load at the output, together with DC supply and a high-impedance output for differential probing using a real-time oscilloscope. In addition a further design provides a monitoring functionality at the drains of the switching transistors in a class-D amplifier for instance, to check the signal waveform before the reconstruction filter. This gives a very interesting new possibility to characterize the intern signal waveform in a switch-mode amplifier.

Index Terms:
Differential measurement, Class-S, Class-D, Amplifier, GaN, HEMT.

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