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:
Nov. 15, 2005
Filed:
Feb. 13, 2002
Haruo Koizumi, Sennan, JP;
Haruo Koizumi, Sennan, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
A demodulator controls gains of an RF-AGC amplifier and an IF-AGC amplifier so as to maintain an input level to the demodulator constant. In this case, the demodulator estimates a signal level of an RF input based on the sum of the gains directed to the both AGC amplifiers, and changes methods for distributing a gain to the AGC amplifiers, according to whether or not the signal level exceeds a predetermined Take Over Point. Further, a first detection and smoothing circuit detects an output level of the RF-AGC amplifier, and a second detection and smoothing circuit detects an output of a mixer. Besides, a comparison circuit controls the gain of the RF-AGC amplifier so that a difference between the output levels comes to be a predetermined value. With this structure, an automatic gain control circuit which can achieve high receiving sensitivity and low waveform distortion simultaneously can be realized even when manufacturing dispersion is caused.