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:
Sep. 29, 2009
Filed:
Apr. 07, 2008
Ko-yang Tso, Jhonghe, TW;
Keh-la Lin, Taipei, TW;
Yann-hsiung Liang, Taichung, TW;
Chin-chieh Chao, Hsinchu, TW;
Ko-Yang Tso, Jhonghe, TW;
Keh-La Lin, Taipei, TW;
Yann-Hsiung Liang, Taichung, TW;
Chin-Chieh Chao, Hsinchu, TW;
Raydium Semiconductor Corporation, Hsinchu, TW;
Abstract
A voltage-clamping device used in an operational amplifier is provided. The operational amplifier comprises a first transistor. The cross-voltage between the gate and the source of the first transistor is near to a specific voltage and the cross-voltage between the drain and the source of the first transistor is not equal to zero, so as to generate a big substrate current. The voltage-clamping device comprises a second transistor whose source and gate are respectively coupled to the drain of the first transistor and used for receiving a bias signal, so that the second transistor is biased in saturation region, and the voltage at the source of the second transistor is made equal to the difference between the bias signal and the threshold voltage of the second transistor. Thus, the cross-voltage between the drain and the source of the first transistor is reduced and the substrate current is reduced accordingly.