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:
Jan. 13, 2004
Filed:
Jul. 08, 2002
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
A charge/discharge circuit creates a carrier detection level based on a received signal in a carrier detector circuit for detecting the presence or absence of a carrier in such applications as a receiver for an IR remote controller. The charge/discharge circuit operates to amplify a current, that is produced in n-type transistors QN , QN , QN and a reference current source, in a p-type transistor QP . The amplified current is mirrored by a current mirror circuit to be supplied as an emitter current of a p-type transistor QP . The charge/discharge circuit charges a capacitor with a small current, i.e., a base current of the p-type transistor QP . The charge/discharge circuit includes a bias voltage source which produces such a bias voltage that the emitter-collector voltage of the p-type transistor QP becomes substantially equal to the emitter-collector voltage of the p-type transistor QP . As a result, it is possible to limit an error of a charge current charged into the capacitor, which is caused by the emitter-collector voltage dependent change of the collector current and thus the base current, known as the Early effect.