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. 01, 1980
Filed:
May. 30, 1978
Daniel D Culmer, Sunnyvale, CA (US);
Ronald W Russell, Sunnyvale, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
An expanded analog-to-digital converter includes a first digital-to-analog converter for converting the most significant bits of digital output signal having a given number of bits to a first analog reference signal having a value that is proportional to the value of the most significant bits minus one-half the least significant bit of the digital output signal whenever the value of the most significant bits is other than zero; and a second digital-to-analog converter for converting the least significant bits of the digital output signal to a second analog reference signal. A successive approximation register successively provides the bits of a digital output signal in accordance with a comparison of an analog input signal with the sum of the analog reference signals. A logic circuit coupled to the successive approximation register for providing an indication of whether the value of the most significant bits is other than zero, causes the second analog reference signal to have a value that is proportional to the value of the least significant bits whenever the value of the most significant bits is other than zero, and a value that is proportional to the value of the least significant bits minus one-half the least significant bit of the digital output signal whenever the value of the most significant bits is zero.