Characterization of In-Phase/Quad-Phase Digital Downconversion Via Special Sampling Scheme

This study explores the characterization of a Special Sampling Scheme (SSS) for In-Phase and Quad-Phase (I/Q) downconversion using mathematical analysis. The SSS is an under-developed signal sampling methodology that can be used with military and industry radar receiver systems. The SSS processes a digital input signal-stream sampled at a specified sampling frequency, and downconverts it into In-Phase (I) and Quad-Phase (Q) output signal-streams. Using the theory and application of the SSS, the main objective to be accomplished is the mathematical characterization of the effects of input, output, and filter coefficient parameters on the I/Q imbalances when using the SSS. We use Matlab to examine and to characterize the SSS to generate parameters suitable for an implementation with a digital circuit.