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:
Feb. 04, 1997
Filed:
Sep. 08, 1995
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A high frequency television signal receiving apparatus providing excellent linear detection of output characteristics by improving the phase characteristic of the picture synchronous detector. A variable capacitive element is equivalently connected in parallel to a reference solid-state oscillation element. The reference solid-state oscillation element controls the frequency of a local oscillation device including a PLL circuit for feeding a local oscillation signal to a mixer for converting a high frequency signal into an intermediate frequency signal. A first low pass filter is connected between a phase comparator for detecting a phase difference of the intermediate frequency signal and the output of a detection oscillator for generating a detection oscillation signal with a specific phase difference. A second low pass filter having a larger time constant than the first low pass filter is connected to the variable capacitive element. The capacitance of the variable capacitive element is varied by the output voltage of the phase comparator. The signal frequency of the local oscillation device is shifted, and is controlled to converge the frequency of the intermediate frequency signal within the frequency range of the detection oscillation signal.