A Low-Noise Transmission-Type Yttrium Iron Garnet Tuned Oscillator Based on a SiGe MMIC and Bond-Coupling Operating up to 48 GHz

Wideband and low-noise tunable oscillators at microwave frequencies are crucial within microwave frequency synthesizers and key to high-end measurement systems based on electromagnetic sensing in the microwave range as well as in the terahertz (THz) and sub-THz range. This paper presents a novel, wideband, and low-noise differential yttrium iron garnet (YIG) tuned oscillator. It is based on a SiGe monolithic microwave integrated circuit and a transmission-type YIG resonator. The integrated circuit contains a fully differential amplifier as a part of the oscillator core. The resonator was realized by two orthogonal, crossed pad-to-pad bonds and an YIG sphere, which is positioned between those bonds and the integrated circuit. To design and optimize the oscillator, an equivalent circuit modeling the resonator was developed. Concerning the tuning range and the phase noise, the results of the circuit simulations are in good agreement with the measurements. Two oscillators with different lengths of the inductive load transmission line were realized. First, the oscillator with a short transmission line offers very high-oscillation frequencies with a tuning range from 32.0 to 48.2 GHz. It exhibits an excellent phase noise of less than -119dBc/Hz at an offset frequency of 100kHz for oscillation frequencies up to 42GHz. Second, the oscillator with a longer transmission line length offers a tuning range from 19.1 to 41.4 GHz. This configuration exhibits an excellent phase noise of less than -120dBc/Hz at an offset frequency of 100 kHz for oscillation frequencies up to 38GHz.