有線電視用多層印刷電路低通濾波器

Abstract

本論文研製之低通濾波器可用在有線電視系統中接收調諧器，和發射輸出 端。以前，製作這種濾波器的方法有兩種，一種是用集中式繞線電感和電 容組合而成；另一種是用分佈式電路技術製作在高介質係數陶瓷多層板上 。前者雖然便宜，但是需要人工長時間來微調電感；後者體積小，品質佳 ，不需要人工長時間來微調電路，但是價錢昂貴，並且目前臺灣尚未有高 介質係數陶瓷多層板製程技術；這種技術掌握在日本人手□，價格更不容 易降下來。鑑於此，我們希望利用臺灣已具有的多層印刷電路技術，和高 頻分佈式電路技術，用傳輸線來取代傳統的繞線電感，達到省人工且便宜 的低通濾器。 The 550-MHz low-pass filters can be used in the headend of transmitting control-center and the set-top tuners. There are two types of such filters. One is lumped filters and the other is ceramic multilayer distributed filters. Lumped filters are usually constructed using parallel-plate chip capacitors and air-wound inductors soldered into a small housing. Skilled manual labor is required o build and tune such a type of filters. Multilayer ceramic distributed filters have better quality, and smaller size, and are easier to fabricate than the lumped filters. They are, however, more expensive than the lumped filters. The techniques of processing multilayer ceramic distributed filters are well developed in Japan, but they are new in Taiwan. Due the high prices of multilayer ceramic distributed filters there is an urgent need to develop a low- cost and time-saving technique for low-pass filters. In Taiwan, the processing techniques of multilayer printed wiring board (ML-PWB) are well developed. By using the techniques of ML-PWB and transmission-line to replace air- wound inductor, we report here a design, fabrication and testing of a low-cost and time-saving multilayer PWB 550-MHz low-pass Filter.