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:
Jun. 12, 2001
Filed:
Sep. 23, 1998
Yukinaga Koike, Nagano, JP;
Circuit Design, Inc., Hotaka-machi, JP;
Abstract
A wireless microphone use UHF band carrier FM transmitter adopting a PLL system, which has a voltage controlled crystal oscillation type modulator (VCXO) for performing FM modulation on an oscillation frequency of a crystal oscillation circuit by an input of a modulation signal AF of an acoustic signal and which uses an FM modulated signal f,obtained from the VCXO as a reference signal V,to be input to an analog phase comparator (PC) of a PLL circuit,. The PC performs a phase comparison operation at a high speed (10 MHz or more), therefore a cutoff frequency of a loop filter (,) may be a high band frequency of about 100 KHz to 1 MHz so that the cutoff frequency considerably higher than the highest audible frequency 20 KHz can be selected. The filter output moves at an inaudible frequency and therefore there is no audible noise generated even due to vibration, feedback, etc. It is also possible to make the charge pump circuit and other steps for shielding against interference and steps for giving resistance to vibration superfluous without adopting the loop filter switching system, therefore a reduction of size and a lowering of cost can be realized.