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. 18, 1989
Filed:
Jul. 15, 1987
James C Fletcher, Washington, DC (US);
Walter L Ross, Simi Valley, CA (US);
Abstract
A digitally controlled resistance generator (10) in which resistors (16-38) having values selected according to an expression 2.sup.N-1 (R), where N is equal to the number of terms in the expression, and R is equal to the lowest value of resistance, are electrically inserted into a resistive circuit in accordance with a parallel binary signal provided by an analog-to-digital converter (46) or a programmable computer (75). This binary signal is coupled via optical isolators (50-72) which, when activated by a logical '1,' provides a negative potential to some or all of the gate inputs (96) of the normally 'on' field effect transistors (98-120) which, when 'on,' shorts out the associated resistor. This applied negative potential turns the field effect transistors 'off' and electrically inserts the resistor coupled between the source terminal (124) and the drain terminal (122) of that field effect transistor into the resistive circuit between the terminals (12, 14).