Synthesis Method of Procedure for Odd-Order I/Q Demodulation Based on Replacing Multistage with Equivalent Single-Stage Demodulation Schemes

Abstract

A method of synthesis of odd-order I/Q demodulators based on replacing the multistage demodulation schemes with equivalent single-stage ones is proposed. The calculation of coefficients of single-stage odd-order I/Q demodulator, which is equivalent to multistage scheme in terms of the waveform of its amplitude-frequency characteristic (AFC), is based on the sample-wise analysis of the process of forming the response of the demodulator output stage that involves the sampling the harmonic signal voltages at the output of analog-to-digital converter (ADC). An example of synthesis of 11-sample former of quadrature components is considered for illustrating the application peculiarities of the method proposed for synthesis of odd-order I/Q demodulators. The comparative results of its AFC calculations are presented. The analytical description of the response of the specified unit in terms of the coefficients of even-order I/Q demodulators forming the multistage scheme has been derived. A number of regularities intrinsic to coefficients of odd-order I/Q demodulators was established, including the regularities characterizing the dependence of their dynamic range on values of weighting coefficients of the initial multistage scheme.