Design of low phase-noise oscillator based on a novel bandpass filter

In this letter, a low phase-noise microwave oscillator based on a narrowband symmetric structure filter using coupled transmission lines is proposed. The novel structure for a narrowband filter is characterized with a low phase noise due to the good quality factor on transmission zero. An oscillator based on the filter was designed, fabricated and measured. At the oscillation frequency of 1.92 GHz, the measured phase noise is - 112dBc/Hz at 100 kHz offset with 5.23 dBm output power and DC-RF power efficiency is 9.7%.