Development of Low Phase Noise Dual-Band Oscillator Using Switchable Bandpass Filter

• Main Authors: Tzung-han Du, 杜宗翰
• Other Authors: Wen-hua Tu
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/87713710613397641242

碩士 === 國立中央大學 === 電機工程學系 === 103 === Stepped-impedance resonators (SIRs) with p-i-n diodes loaded at one end are used to switch resonant condition of the stepped-impedance resonators and develop switchable bandpass filters in this paper. Due to distributed coupling technique, the advantage of low loading effect is used in switchable multi-band bandpass filter and extend to the parallel feedback oscillators as frequency selector. The switchable tri-band bandpass filter consisted of half-wavelength/quarter- wavelength resonator. Each passband is operating by a respective pair of resonators, and the three BPFs are combined by utilizing distributed coupling technique to decrease channel-to-channel loading effect. The diodes are loaded at the end of the resonators as the switching devices to independently switch the three passbands. The switchable bandpass filter mentioned above is used in parallel feedback oscillators as frequency selector to develop dual-band oscillator. The stepped-impedance resonators also reduce 30％ circuit size. To achieve a low phase noise, the oscillation frequency is designed at the peak of complex quality factor of the filter to improve the phase noise. A low phase noise dual-band oscillator is presented.