Analysis of quadrature detectors using complex envelope notation

Quadrature detection is a common technique for demodulating radio and microwave signals in which the signal is demodulated to form two orthogonal components. Complex envelope notation is a compact method of representing the modulation of a real signal in complex form. The relationship between these two concepts is discussed, and there follows an analysis of quadrature demodulation including the effects of gain mismatch, phase error, local oscillator breakthrough and DC offsets.