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. 09, 1998
Filed:
May. 14, 1996
Dennis A Dempsey, Limerick, IE;
Michael Gerard Tuthill, Limerick, IE;
Martin Gerard Cotter, Ennis, IE;
Analog Devices, Inc., Norwood, MA (US);
Abstract
A switch architecture for a digital-to-analog converter provides improved linearity. A first switch for one leg of the R/2R resistance ladder includes a unit resistor coupled between the MOSFET devices of the switch and the respective leg of the R/2R ladder. The on resistances of the MOSFET devices of the first switch are controlled in response to a reference value, such as the resistance of a reference resistor, which may have a resistance and other characteristics similar to the unit resistor. Other switches for other legs of the R/2R ladder also have a unit resistor, or other MOSFET devices having an on resistance controlled in relation to the reference value. Additional switches for other legs of the R/2R ladder may also have MOSFET devices of varying width to channel (W/L) ratios. Each of these approaches may be combined to achieve a binary weighting or an alternate weighting between legs of the R/2R ladder, in order to provide low linearity error.