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:
Jun. 21, 1994
Filed:
Jun. 29, 1993
James R Butler, San Jose, CA (US);
Analog Devices, Inc., Norwood, MA (US);
Abstract
The gain of a folded cascode operational amplifier is enhanced by connecting the current circuits of added compensation transistors to supply the current circuits of pre-existing gain transistors. Changes in the current through the primary gain transistor resulting from a change in the output load produce approximately equal changes in the base currents of both the primary gain and primary compensation transistors. The change in the compensation transistor's base current is transmitted through the amplifier circuitry to supply the change in the gain transistor's base current, rather than forcing a change in the input voltage differential to supply this current. The differential input signal is thus less sensitive to changes in the output, resulting in higher transconductance and gain. Providing a similar compensation loop for a second gain transistor through the second compensation transistor produces a circuit balance that lowers both the circuit's offset voltage, and the temperature dependence of the offset voltage.