| 摘要 |
<p>A band-pass filter and gain stage which produces a desired passband at a preselected center frequency. The present invention can be characterized as being a very passive frequency door whose output is lightly coupled to a broad band frequency amplifier having a high gain. The present invention includes an input (10) connected to an input impendance stage (12), which is connected to a monolithic filter stage (14), which is connected to a second impendance stage (16), which is connected to a gain stage (18), which, in turn, is connected to an output terminal (20). A piezoelectric quartz crystal monolithic filter (14) or a piezoelectric ceramic monolithic filter (14) can be employed depending on the width desired for the passband response.</p> |
