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:
May. 06, 1986
Filed:
May. 18, 1984
Thomas Hornak, Portola Valley, CA (US);
Gary L Baldwin, Palo Alto, CA (US);
Ronald W Potter, Saratoga, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A binary scaled current source in which a set of binary switches M.sub.1, . . . , M.sub.n controllably switch a current I to a selected one of a set of n outputs. Each switch M.sub.k is controlled by an associated control signal B.sub.k having a duty cycle of 2.sup.k-n-1. At any given time one and only one of the control signals is high so that the current I is diverted to the kth output a fraction 2.sup.k-n-1 of the time. In two particular schemes referred to as the weighted pulse width (WPW) and the weighted repetition rate (WRR) schemes, all of the control signals are periodic with a group pattern repetition period T. In the WPW scheme, B.sub.k has in each period T a single pulse of duration 2.sup.k-n-1 *T. In the WRR scheme, B.sub.k has in each period T2.sup.k-1 pulses each of duration 2.sup.-n *T. The output of each binary switch is typically passed through a low pass filter which conducts substantially only the dc component of the output current from the binary switch to which it is connected. These dc components serve as a set of binary scaled dc currents. Pulsing switches are also added between the source of current I and the binary switches to provide the current I in pulses that do not overlap any of the transitions in the control signals so that the binary scaled currents that are produced are insensitive to timing of the transitions in the control signals.