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:
Oct. 28, 2003
Filed:
Mar. 29, 2002
Dale A. Potter, Beaverton, OR (US);
Lattice Semiconductor Corporation, Hillsboro, OR (US);
Abstract
A comparator circuit is disclosed that senses a differential input polarity even when operating with a common mode voltage near the power rails (e.g., 50 millivolts) and under a wide range of process, temperature, and power supply conditions. In one aspect, the comparator circuit uses a complementary pair of P-type and N-type differential amplifiers. A combined P-type and N-type differential amplifier provides good transconductance even with a common mode voltage near either voltage rail. Consequently, a larger current swing than prior art circuits is provided to a current-to-voltage converter, which results in an overall faster circuit. In another aspect, a bias circuit drives a source follower that biases transistors in the differential amplifiers to ensure high transconductance and, consequently, high gain. Thus, the disclosed comparator senses differential input polarity even with a common mode voltage of only 50 millivolts or less.