| 摘要 |
A narrow band-pass filter interferometric filter (20) for applying a response characteristic to an input signal (24) to produce a filtered output signal. The filter comprises an amplifier (22) having a first input for receiving the input signal (24), an interferometric processing circuit (26) coupled between an output and a second input of the amplifier (22) for producing a feedback signal having a generally constant positive amplitude except for a null at a pass frequency of the response characteristic for the filter. The signal processing circuit (26) may include a phase shift circuit for shifting the filtered out signal by 180 degrees or a delay time circuit for delaying the filtered output signal by a time period generally equal to the period required for the input signal (24) to oscillate through one-half of a cycle. The time delay circuit is implemented using a cable which imparts a time delay to a signal propagating therealong.
|
