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:
May. 12, 2009
Filed:
Sep. 29, 2005
Kouichi Hanada, Kyoto, JP;
Masanori Kayama, Kyoto, JP;
Naohiro Nomura, Kyoto, JP;
Akira Noguchi, Kyoto, JP;
Kouichi Hanada, Kyoto, JP;
Masanori Kayama, Kyoto, JP;
Naohiro Nomura, Kyoto, JP;
Akira Noguchi, Kyoto, JP;
Rohm Co., Ltd., , JP;
Abstract
An operational amplifier includes a differential amplifier circuit provided at an input stage and an amplifier circuit at a post stage. In the differential amplifier circuit, first and third bipolar transistors are PNP-type bipolar transistors and Darlington-connected. An inverting input terminal is connected to the base terminal of the first bipolar transistor. The first and third bipolar transistors and second and fourth bipolar transistors construct an input differential pair. First and second protection diodes are connected between the base terminals of the first and second bipolar transistors constructing the input differential pair and the ground potential, respectively. Each of the protection diodes is connected so that the cathode terminal is positioned on the base terminal side of the bipolar transistor, and the cathode terminal is positioned on the ground potential side.