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:
Apr. 30, 2002
Filed:
Jun. 08, 2000
Damien McCartney, Limerick, IE;
Analog Devices, Inc., Norwood, MA (US);
Abstract
An operational amplifier having two differential input stages. A first one of the stages comprises a pair of first input transistors and another one of such stages comprises a pair of second input transistors. The second input transistors are complementary in type to the first input transistors. A comparator is fed by a sense signal and a reference signal, such sense signal being related to at least one of a non-inverting and an inverting input signal fed to the operational amplifier. The comparator produces a control signal in accordance with a difference between the sense signal and the reference signal. A switching network is responsive to the control signal and couples an output of either the first one of the stages or the second one of the stages to an output of the operational amplifier selectively in accordance with the control signal. An input chop circuit is adapted for coupling to a differential input signal, formed by the non-inverting and inverting input signals, and for providing the differential input signal with a non-inverted polarity during a first time period and such differential input signal with an inverted polarity during a succeeding time period. The differential input signal with the provided inverted polarity and the provided non-inverted polarity are fed to the coupled one of the two stages during the first time period and the succeeding time period, respectively. With such an arrangement, transitional regions where one of the stages that are coupled to the amplifier output is partially operational are eliminated, thereby reducing errors that occur in these transitional regions.