A Subharmonic Injection-Locked Self-Oscillating Mixer

A subharmonic injection-locked self-oscillating mixer (s-ILSOM) at 1 GHz is reported in this paper. The proposed circuit which combines both injection-locking and mixing functions is described theoretically and experimentally. In contrast to previously reported works, only one input port is required for both the RF/IF signal and the injection signal. Furthermore, the injection signal which is used to stabilize the oscillation is at a subharmonic of the oscillation frequency (f_LO/4), with a power level as low as -20 dBm. Phase noise calculations and mixing characteristics are reported, indicating a noise improvement, and a high up-conversion gain for both fundamental and harmonic mixing. The circuit is implemented, using a GaAs FET, exhibiting an up-conversion gain of 13 dB, a phase noise of -93 dBc/Hz at 100 KHz offset, a P_1dB of -18 dBm, an IP3 of -5 dBm, and a power consumption of 24 mW.