帶通與帶阻濾波器.ppt

第10單元 帶通與帶拒濾波器之設計與製作,帶通與帶拒濾波器之設計與製作,Band Pass Filter Design,Transformation form Low Pass to Band Pass,Frequency,Elements Transformation form Low Pass to Band Pass,Band Pass Filter Design,Shunt Element becomes Parallel-Resonant Series Element becomes Series-Resonant,BPF Frequency and Impedance Scaling,For Parallel-Resonant Branches:,For Series-Resonant Branches:,Where,R=The Final Load Impedance B=3-dB Bandwidth fo=The Center Frequency Ln=normalized Inductor Cn=normalized Capacitor,Summary of the Bandpass Filter Design Procedure,1. Transfer the Bandpass requirements into equivalent low-pass requirements. 2. Refer to the low-pass attenuation curves provided in order to find a response that meets the requirements of step1. 3. Find the corresponding low-pass prototype and write it down. 4. Transform the low-pass network into a bandpass configuration. 5. Scale the bandpass configuration in both impedance and frequency.,BPF Design Example,Ex. Design a BPF with the following requirement,fo = 75 MHz BW3 dB = 7 MHz BW45 dB = 35 MHz,Passband Ripple = 1 dB RS = 50 ohms RL = 100 ohms,Sol:,參考13-22頁之右圖可知，n = 3時之Chebyshev 可滿足設計之需求。,參考相關書本可得低通濾波器之雛形電路圖。,將前面所得之低通濾波器之雛形電路圖轉成帶通濾波器之 雛形電路。,Low-Pass Prototype,Band-Pass Prototype,參考14-4頁可得,二階帶通濾波器 帶通濾波器可由低通與高通濾波器串連而成,簡易二階 RLC 被動帶通濾波器,Band Rejection Filter Design,Design approach similar to band pass filter,Transformation form Low Pass to Band Rejection,Shunt Element becomes Shunt Series-Resonant Circuits Series Element becomes Series Parallel-Resonant Circuit,BRF Frequency and Impedance Scaling,For Series-Resonant Branches:,For Parallel-Resonant Branches:,Where,R = The Final Load Impedance B = 3-dB Bandwidth fo = The Center Frequency Ln = normalized Inductor Cn = normalized Capacitor,70 MHz 帶通濾波器,帶通濾波器之頻率響應量測結果,帶通濾波器之輸出入返回損耗量測結果,帶通濾波器之介入耗損量測結果,900 MHz 帶拒濾波器,帶拒濾波器之頻率響應量測結果,帶拒濾波器之輸出入返回損耗量測結果,帶拒濾波器之介入耗損量測結果,濾波器類型之比較,Character,Type,