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

Abstract: This letter presents a 360{\deg} phase detector cell for performing phase-shift measurements on multiple output systems. An analog phase detector, capable of detecting a maximum range of {\pm}90{\deg}, 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 ({\Phi} < 90{\deg} {\pm} 90{\deg}) is discussed by using four straight-line equations to characterize the phase detector response. The proposed solution allows to extend up to 360{\deg} 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{\deg} {\pm} 0.5{\deg} 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{\deg} ({\pm}180{\deg}) across the tested frequency band of 2.7-6 GHz.