A Simple Method for Sampling In-Phase and Quadrature Components

We present a method of developing in-phase and quadrature samples of a band-limited RF waveform. The problem of matching gain and phase response differences between the two components is avoided by a combination of mixing to an IF frequency, sampling and digitizing, and digital filtering. The novelty of the method is in the design of the digital filter, which is realized as a pair of 900 phase splitting networks with several symmetries which are exploited to save computation.