在語音與電子音樂合成系統中需使用濾波器來選擇頻率影應，傳統的電子合成系統使用被動濾波器(passive filters)，設計複雜度高且體積大，本研究以活性濾波器(active filter)取代被動濾波器，以簡化系統之複雜度。
本研究先分析活性濾波器之各種電路，然後再以此些電路設計適合各種樂器之活性濾波器，以模擬各種樂器之頻率響應。最後以實驗數據分析活性濾波器所模擬之電子合成器之結果。
Filters are used very often in voice and electronic music synthesis, they are applied to imitate the voice or the timbre of various musical instruments. Most traditional electronic organs use passive filters designed around combinations of inductors and capacitors to build the instrument filters. Today active filters are often a better choice for the voicing of electronic music synthesizer. In this report active filter circuitry is analyzed first, and the instrument filters are designed based on this circuitry, then the frequency-response curves of the instrument filters are observed on the spectrum analyzer. Finally an electronic tone generator is built to test the performance of the instrument filters.
