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:
Dec. 08, 1987
Filed:
Dec. 20, 1985
Franciscus A Schoofs, Eindhoven, NL;
Martinus P Bierhoff, Eindhoven, NL;
Job F Van Mil, Eindhoven, NL;
Albert H Slomp, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A D/A converter providing a binary weighted series of currents (I.sub.3, I.sub.4, I.sub.5) via first current-source transistors (T.sub.3, T.sub.4, T.sub.5) each in a given ratio to a reference current (I.sub.1) in a reference transistor (T.sub.1). The weighted currents are switched to analog output (15) or to positive supply terminal (20) via first switching devices (3.1, 3.2, 3.3). A control device includes a second current-source transistor (T.sub.8) connected to a reference-current source or to the positive supply terminal via a second switching device (4). The current (I.sub.8) in the transistor T.sub.8 has a given ratio to the reference current (I.sub.1). By connecting the second current-source transistor to the positive supply terminal or to the reference current source, the reference transistor carries the full reference current (I.sub.ref) from the reference current source or only a fraction of the full reference current, respectively. As the weighted currents are in a given ratio to the current (I.sub.1) in the reference transistor, these currents are a similar fraction smaller in the first case than in the second case. By increasing the reference transistor current (I.sub.1) stepwise from a fraction to the full reference current over the range of the digital input code, the converter output current range will also vary stepwise.