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:
Dec. 15, 1981
Filed:
Dec. 17, 1979
Roubik Gregorian, Santa Clara, CA (US);
American Microsystems, Inc., Santa Clara, CA (US);
Abstract
An elliptic state variable filter uses switched capacitors controlled by an arrangement of switches that provides for a frequency response independent of stray capacitors in the circuit. The filter section comprises three integrating operational amplifiers connected in series, with a feedback connection between the output of the second operational amplifier and the circuit input to the first operational amplifier. Signals via a feed forward connection from the circuit input and the outputs of the first and second operational amplifier are summed by the third operational amplifier. Transmission zeros of the filter transfer function are realized independent of poles and with a feed forward arrangement which places them inherently on the unit circle and produces infinite loss at each zero frequency despite variations in capacitor ratios in the circuit.