360° phase detector cell for measurement systems based on switched dual multipliers

Abstract

This letter presents a 360° phase detector cell for performing phase-shift measurements on multiple output systems. An analog phase detector, capable of detecting a maximum range of ±90°, has been used to perform a double multiplication of two signals, both in-phase and phase-shifted. The proposed solution broadens the frequency range beyond other solutions that require to fulfill the quadrature condition. Subsequently, the possibility of reaching the theoretical limit of phase shift within a hybrid coupler (Φ < 90° ± 90°) is discussed by using four straight-line equations to characterize the phase detector response. The proposed solution allows to extend up to 360° the phase detection range and provide an increased immunity with respect to both impedance mismatching and phase deviations within the hybrid coupler. To demonstrate the feasibility of the proposed design, a phase detector cell prototype has been implemented using a commercial hybrid coupler with a phase shift of 92.5° ± 0.5° at 3.1-5.9 GHz, an external switch and a microcontroller with 2 kB of memory. Measurements show a range of detection of 360° (±180°) across the tested frequency band of 2.7-6 GHz.