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:
Aug. 16, 1983
Filed:
Jun. 06, 1980
James P Ballantyne, Wyomissing Hills, PA (US);
Paul E Fleischer, Little Silver, NJ (US);
Kenneth R Laker, Staten Island, NY (US);
Aristides A Yiannoulos, Wyomissing Hills, PA (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
A capacitor-resistor-capacitor (CRC) element for active filter realization, which is fully integrable and compatible with MOS technology, is described. The incorporation of the CRC element in a semiconductor integrated circuit active filter also is described. The structure of the CRC filter element is closely analogous to a depletion mode MOS field effect device, except that the channel zone 26 is doped to a level which substantially precludes conductivity modulation at the usual operating voltages. However, the doping level is such as to enable the use of the channel zone as a semiconductor resistance element. Thus, the N-channel CRC element realized in the NMOS technology comprises a first capacitance composed of the gate 27, gate dielectric 38, and resistive channel 26, paralleled by the resistive channel 26 itself constituting a resistor, and then the underlying PN junction capacitance between the N-type resistive channel 26 and the underlying P-type semiconductor body portion 21. An active low-pass filter consists of two CRC elements and an operational amplifier and utilizes the positive feedback principle.