The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 13, 1976
Filed:
Jul. 03, 1975
Masaru Asahara, Kawasaki, JA;
Noriyasu Toyonaga, Tokyo, JA;
Hiroaki Ohyama, Tokyo, JA;
Hiroshi Nakamura, Sagamihara, JA;
Ryushiro Yoshizawa, Yokohama, JA;
Fujitsu Ltd., , JA;
Abstract
Band pass filter circuit for a band pass filter which detects a phase difference between input and output signals of said band pass filter, and the detected output controls, via a low pass filter, a voltage controlled oscillator, the output of which controls first and second mixers connected respectively to an input side and an output side of the band pass filter, so that the output of the first mixer can be maintained at the center frequency of said band pass filter. Further, when an irregularly timed signal is received, before an input signal is pulled in the synchronized state, said band pass filter is provided with a wide pass band so as to pull the signal in the synchronized state in rapidly. After said input signal is pulled in said center frequency, the pass band of said band pass filter is changed to a narrow bandwidth so as to improve the quality of the noise and at the same time, a cutoff frequency of said low pass filter is changed to a lower frequency side so as to improve the stability of the band pass filter circuit.