Design of voltage-controlled oscillator with compact size and wide tuning range

摘要

In this paper, a novel frequency-tunable filter based low noise voltage-controlled oscillator (VCO) is proposed. The proposed tunable filter consists of a T-type resonator with four varactors and a pair of short-ended stubs connected with feedlines. High-Q can be achieved by introducing a transmission zero on the upper stopband, which can reduce the phase noise of the VCO. The whole size of the tunable filter is 0.002λ^{2_g. The proposed VCO was fabricated and measured indicating a promising frequency-tuning range from 2.2 to 3.2 GHz with the second harmonic suppression level of better than 22 dB. The measured phase noise is -88-91.44dBc/Hz at 100KHz offset.}