Abstract: An RF/Microwave oscillator is disclosed that has the high-Q, low-loss, and phase noise performance of a DRO, without the need of a dielectric resonator to achieve such performance. The RF/Microwave oscillator includes a field effect transistor having a drain coupled to an output circuit, a source coupled to a series feedback circuit, and a gate coupled to a resonator circuit. Each of these circuits are comprised of cascaded pairs of coupled transmission lines designed to resonate at the operating frequency of the oscillator. The RF/Microwave oscillator may also include a frequency-adjustable bias circuit, a frequency-adjustable FET gate return, and a frequency tuning circuit.

Abstract: A frequency-adjustable direct current biasing circuit is disclosed for providing a DC bias voltage or a DC connection to ground for an RF or microwave circuit without substantially affecting the RF or microwave signal of the circuit. The biasing circuit includes a transmission line having a first portion for connection to the RF circuit and a second portion connected to a low-impedance-to-ground structure, such as a bypass capacitor or a DC path to ground. The electrical length between the first and second portions is about 90 degrees. The biasing circuit further includes an open ended tuning stub coupled to the transmission line that has a length that is adjustable. By adjusting the length of the tuning stub, the biasing or grounding circuit can provide better isolation for RF energies at different selected frequencies. Also disclosed herein is a dielectric resonator oscillator (DRO) that uses the frequency-adjustable biasing circuit.