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:
Jul. 06, 1999
Filed:
Jun. 12, 1998
Dan Ion Hariton, Pinole, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A compensated, bias-dependent signal filtration and amplification circuit includes a low-pass RC filter with a bias-dependent frequency response caused by the use of MOS transistors connected as capacitors with bias-dependent capacitances. A dc current source is used, in cooperation with the resistors of the RC filter, to generate a fixed bias for the capacitor-connected MOS transistors and thereby eliminate the bias dependencies of the capacitances. Following amplification of the filtered signal, another dc current is subtracted out from the amplified output signal so as to eliminate any residual dc signal components due to the input compensation dc bias signal, thereby leaving only the amplified filtered ac signal components.