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. 30, 1999
Filed:
Jan. 20, 1998
Salman Mazhar, Bloomington, MN (US);
Marius Dina, Burnsville, MN (US);
William W Leake, Eagan, MN (US);
VTC Inc., Bloomington, MN (US);
Abstract
An integrated, tuning circuit for tuning a MOSFET-C filter contains a tuning MOSFET and a differential amplifier. A current source is connected to the drain of the tuning MOSFET. The output of the amplifier is coupled to the drain of the tuning MOSFET and to a terminal that connects to the drains of the MOSFETs of the filter, so that the equivalent resistance of the filter is dependant on the current. The current source is coupled to a reference current generator, such that current supplied by the current source to the tuning MOSFET is proportional to the current supplied in the reference current generator, which in turn varies with process and environmental conditions of a capacitance. As a result, changes in process and environmental conditions oppositely affect the capacitance and resistance in the filter, resulting in a fixed RC product and fixed frequency response from the filter.