Injection Locked Oscillator for Radiometer

Abstract

The main goal of this project was to design an injection locked oscillator (ILO) with free-running frequency of 70 GHz, and with locking capability to the third and the fifth harmonics of the reference signal upon injection. The circuit was realized using the silicon-germanium (SiGe) bipolar-complementary metal-oxide-semiconductor (BiCMOS) technology and the locking condition were verified after simulating the resistor-capacitor (RC) extracted netlist of the layout. The cadence virtuoso toolkit was used for the design process and the simulation purpose. The locking phenomenon, quasi-lock and fast-beat mode, lock range upon different injection power and phase noise characteristics of the ILO upon subharmonic injection were studied.

The ILO was implemented using the direct (parallel) injection topology. The designed ILO circuit consists of two main components; conventional cross-coupled oscillator with oscillation frequency of 71 GHz and harmonic generator that injects the harmonics of the reference signal into the oscillator. The nonlinearity of the transistor was studied under different biasing conditions and the optimal bias point of 0.83 V was chosen that provided the maximum frequency conversion gain. The power consumed by the core oscillator is 2.64 mW and 3.4 mW by the harmonic generator under the supply voltage of 1.2 V, making the total power consumption of 6.04 mW as a whole by the ILO.

The ILO achieved the locking range (LR) of 7.9% for the fifth harmonics injection and 1.22% for the third harmonics injection of the reference signal with input injection power of 0 dBm. The oscillator even achieved 0.32% LR for the seventh harmonics injection with the injection power of 0 dBm. The corresponding frequency ranges are 18.9-24.5 GHz, 13.29-14.16 GHz, 9.8-10.03 GHz for the third, fifth and the seventh harmonics respectively.