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A Simple Optimization Method for Generating High-Purity Amplitude and Phase Modulation



Archita Hati, Craig Nelson


We present a simple method for the adjustment of an in-phase (I) and quadrature-phase (Q) Armstrong type modulator for use as a calibrator in precision noise metrology. The availability of relatively pure levels of both amplitude modulation (AM) and phase modulation (PM) can greatly simplify the optimal alignment and calibration of metrology equipment such as AM and PM noise measurement systems. The phase and amplitude imbalance of the components that constitute an IQ modulator results in an undesired combination of AM and PM. These impairments must be corrected to generate the pure signals required for metrology. Our proposed method corrects for these non-ideal impairments and offers nearly ideal operation of the modulator without needing any additional hardware. We present calibration procedure and error analysis of such a modulator when used as a calibrator for a PM and AM noise measurement system.
IEEE Transactions on Instrumentation and Measurement


Amplitude modulation, Armstrong modulator, Phase modulation, Phase noise, IQ modulator, Single sideband (SSB) modulation, Uncertainty


Hati, A. and Nelson, C. (2022), A Simple Optimization Method for Generating High-Purity Amplitude and Phase Modulation, IEEE Transactions on Instrumentation and Measurement, [online],, (Accessed April 22, 2024)
Created June 27, 2022, Updated May 22, 2023