Double mixer broadband phase shifter - has single oscillator feeding second mixer directly and input mixer via ninety degree narrow band phase shifter

摘要

The phase shifter circuit includes a phase shift unit whose bandwidth is lower than that of the operating frequency band. The input signal is applied to an input mixer (M) whose output passes via a first low pass filter (TP1) to a second mixer (R). The second mixer's output is filtered by a second low pass filter (TP2). A single oscillator (O) is connected directly to the second mixer and indirectly via a 90 deg. phase shifter (P) to the input mixer. The two filters only allow the difference frequencies from their respective mixers to pass through.