Band stop type filter circuit

Abstract

Abstract PURPOSE:To increase the Q without increasing the shape of a filter circuit by providing an active element coupled in common to plural resonance circuits, operated when the resonance circuits are in the resonance state and causing a negative resistor. CONSTITUTION:A transmission filter 12 is formed by series connection between 3-stage of band-pass filters 16 and 4-stage of band-stop filters 18, the band-pass filters 16 are designed for comparatively wide band and its attenuation region is parted greatly from a desired frequency. Then an undesired frequency signal is stopped by the band-stop filters 18. A resonator of the band-stop filters 18 is combined with an active element T. The resonance circuit R is resonated with the attenuation region of the band-stop filters 18, the active element T is operated to show a negative resistance. Thus, energy is supplied from the active element T to the resonance circuit T. That is, in adjusting the Qex between the resonance circuit R and the active element T equal to the specific Qo to the resonance circuit R, the apparent Q of the resonance circuit R becomes a very large value.

Inventors

• 👤 Yohei Ishikawa
• 👤 容平 石川
• 👤 Hiroaki Tanaka
• 👤 裕明 田中

Bibliographic Details