Design and Analysis of an Injection-Locked Third Harmonic Self-Oscillating Mixer

In this work, an injection-locked third harmonic self-oscillating mixer has been designed for its use as a variable phase-shifter in an active microstrip phased antenna array. The novel circuit design provides the double functionality of variable phase-shifter and down-converter. Maximum conversion gain is obtained, through the optimization of a new multiharmonic load at the input of the circuit. The ranges of synchronized operation are analyzed versus the circuit parameters and the corresponding phase-shifts are calculated. An 11.3-1.55 GHz down-converter with a 3.25 GHz free-running frequency has been designed, providing a theoretical phase-shift variation at intermediate frequency up to 540deg, with a 3.9 dB conversion gain