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. 24, 2002
Filed:
Sep. 08, 2000
Robert J. Brewer, Lambourn, GB;
Analog Devices, Inc., Norwood, MA (US);
Abstract
An improved chopped CMOS operational amplifier that includes a modulator having differential input and output connections, an AC amplifier coupled to the modulator output, a demodulator coupled to the AC amplifier output, and an integrator coupled to the demodulator output. The improvement is realized in that the operational amplifier has a gain path comprising at least four inverting amplifiers, wherein three or a greater odd number of the inverting amplifiers comprise an integrator that is rendered stable by incorporating a nested integrating capacitor within the integrator, and at least one of the inverting amplifiers is coupled to the modulator output and configured as the AC amplifier. In another aspect of the invention, a second demodulator is introduced to derive a compensating signal that tends to counteract offset voltage components attributable to modulator switch mismatch. In a further aspect of the invention, an interface network is inserted between the modulator and the AC amplifier to open the main signal path during transitions of the modulator clock signals.