An 8.2-to-21.5 GHz Dual-Core Quad-Mode Orthogonal-Coupled VCO with Concurrently Dual-Output using Parallel 8-Shaped Resonator

Abstract

Software-defined radio transceivers, wireless infrastructure equipment, and test equipment require the local oscillator (LO) to cover a very wide range of the output frequencies while meet the phase noise performance. The most straightforward method for a wide tuning range is to adopt multiple separated oscillators. However, this method suffers from the bulky area and relatively complicated multiplexing functions. The authors in [1] introduces triple-coupled inductors that create multiple resonant frequency in a high-order resonator. Nevertheless, the impedance magnitude looking into either port of the high-order resonator shows higher peak value at the lower resonant frequency, which makes it difficult to sustain stable oscillation at higher resonant frequency when the coupling factor is large. The VCO in [2] exploits series 8-shaped coils to generate two oscillation modes without coupling between each other while occupying compact area. However, the quality factor of the 8-shaped inductor is considerably lower than a typical octagonal inductor thereby degrading the oscillator phase noise. In order to solve the above-mentioned issues, a dual-core quad-mode orthogonal-coupled VCO using parallel 8-shaped resonator is proposed. Each core in the proposed VCO have two modes, with one mode being equivalent to the 8-shaped inductor, which allows both cores to be orthogonal to each other by proper configurations.