A new dual-tone, signal-normalisation method for the measurement and prediction of small-signal distortion

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1 Scopus citations


A new method for characterising small-signal distortion is introduced. This novel gain-compression measurement approach employs a ratio of high- and low-level tones, closely spaced in frequency, which are simultaneously measured. A theoretical analysis of two tones passing through a weakly nonlinear device under test is used to demonstrate this new procedure for recovering the gain-distortion (i.e. power series) coefficients from the dual-tone measurement data. The signal normalisation procedure is also shown to effectively remove the time-varying errors associated with the linear receiver circuitry, thereby providing a high level of measurement accuracy. Test results for two amplifiers show that the gain-distortion coefficients can be used to accurately predict the amplifier's weakly nonlinear behaviour at low input power levels for different amplitude offsets between the high- and low-level tones. Although this new technique is demonstrated by using a power-series representation to estimate the small-signal gain compression at the fundamental frequency for memoryless devices, the general techniques that are developed here for this relatively simple problem can be extended to more complex problems where a Volterra series representation is required.

Original languageEnglish (US)
Pages (from-to)11-27
Number of pages17
JournalInternational Journal of Electronics
Issue number1
StatePublished - Jan 2009


  • Gain compression
  • Instrumentation
  • Nonlinear measurements
  • Simultaneous calibration

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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