Published by: Mi-Wave© (Millimeter Wave Products Inc.)
Authored by:  Lokesh Saggam, Shashi Saggam

Abstract—-Harmonics are unwanted frequencies generated by system nonlinearities. They are multiples of the fundamental test frequency. RF power amplifiers are responsible for most of the unwanted harmonics. This paper discusses about harmonic distortion and power measurement of W-band X6 Multiplier with 15 dBm Output Power. Two methods of Harmonics measurement are compared, and their accuracy is discussed here.

I. INTRODUCTION
Harmonics are unwanted frequencies generated by system nonlinearities. They are multiples of the fundamental test frequency and generally, the higher the multiple, the less the amplitude of the harmonic. All “real” test systems have a finite amount of nonlinearities and thus, exhibit some degree of harmonic distortion. The test engineer must ultimately determine acceptable levels of harmonics. His determination is primarily based on test standard mandates. In RF testing applications, RF power amplifiers are responsible for most of the unwanted harmonics. 5th harmonic is higher due to high gain amplifier after the multiplier MMICS which is used inside the circuit to achieve the 15 dBm of output power. Figure 1. shows the Gain of MMIC Amplifier which is higher around 78.35 GHz and is contributing to the issue of lower rejection level for 5th Harmonic.