All pass filter implementation using reflection coefficient of lossless networks

All pass filters are increasingly important as components in digital communications systems, and, although digital baseband realizations are increasingly important, passive analogue filters remain the lowest cost implementations and those with the lowest power consumption for many radio applications. Conventional approaches are based an two port networks with bridged T and lattice structures. These require accurate matching of components to maintain the all-pass characteristics. This paper describes theoretical work and the results of simulation and experiment on the implementation of all pass networks and the related problem of voltage controlled phase shifting networks (for such applications as diversity combining) based on the reflection coefficient of lossless networks