Wide-band π/2 phase shifter using a stepped sweeping dual phase-locked loop technique

Abstract

A wide-band π/2 phase shifter based on stepped sweeping phase-locked loops (PLLs) is introduced and constructed. Results indicate that the system can work over a wide range of input frequencies limited only by the gain and saturation of the voltage-controlled oscillator (VCO) of the PLLs. For a noise-free signal, the phase error between the input and the π/2 phase-shifted output is 3° and it is constant regardless of the input frequency. The system can be modified to produce any phase shift from 0 to n with the same performance.