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:
Jul. 10, 1990
Filed:
Feb. 08, 1989
Burr-Brown Corporation, Tucson, AZ (US);
Abstract
A dual successive approximation analog-to-digital converter, including circuitry for generating separate reference voltages for each analog-to-digital converter, is integrated onto a single semiconductor chip. A single successive approximation register including a 19 bit shift register and two 18 bit latches and associated gating circuitry operates to produce two sets of 18 successive approximation numbers, one supplied as successive digital inputs to a CDAC of one of the analog-to-digital converters and the other set of successive approximation numbers being applied as digital inputs to a CDAC of the other analog-to-digital converter. A CMOS comparator includes two high speed, low gain differential amplifier stages, the first including cascode MOSFETs to provide a high power supply rejection. A pair of auto-zeroing capacitors and a pair of auto-zeroing MOSFETs operate on the outputs of the second differential amplifier to reduce input offset voltage, achieving high speed, low noise operation in a small amount of semiconductor chip area. The auto-zeroed output is supplied to the input of a two stage differential amplifier, the outputs of which also are auto-zeroed and applied to a differential CMOS latch, thereby providing a high speed, low noise, low offset CMOS comparator.