Application of Quasi-Bandpass Filter in 3.5 GHz Microstrip Oscillator

In this paper, a microstrip oscillator working at 3.5 GHz is demonstrate for 5G application. To reduce its phase noise, a quasi-bandpass filter is chosen as its frequency selection network, which utilizes an E-shape dual-mode stepped impedance resonator (SIR). For demonstration, an oscillator example was fabricated and measured. It works at 3.52 GHz and the phase noise is -122.23 dBc/Hz@100 kHz. It achieves the lower phase noise than other counterparts in some literatures do.