Purpose: provide phased outputs for use by a quadrature sampling detector (QSD), such as the Tayloe Detector
Pro: requires 2 X LO frequency, Ultra-broadband,
Con: slightly inferior phase and amplitude balance, some lag or phase difference
However, for a perfect quadrature phase shift, it is difficult to beat a digital phase splitter. The circuit is very simple – it takes 4 times the frequency required and does not use any NOR gate.
The result is two outputs that are in quadrature with each other. It is implemented with two D flip-flops with the inverted signal connected to the input.
This is then fed into a representation of MUX logic that would allow a signal to be sampled at 4 times per cycle of the incoming signal. This is typically done with capacitors, which hold the charge voltage long enough to be sent to an op-amp.
