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:
Jan. 28, 1997
Filed:
Mar. 08, 1995
William N Schnaitter, San Ramon, CA (US);
Alliance Semiconductor Corporation, San Jose, CA (US);
Abstract
A switchable current source (10) for video DACs that reduces output transients. The switchable current source (10) includes a current mirror (20) connected to a cascode pair (22) for providing a reference current input and a current output. Connected to the reference current input is reference current generator (14) that includes p-channel transistor Q5 for providing a reference current according to the voltage applied at its gate by voltage source (24). A current switch (16) is connected to the current output and includes p-channel transistor Q6 for providing a path to ground and p-channel transistor Q7 for providing a path to an output node. In response to a decoder input DEC, an enable signal generator (18) outputs an enable signal EN and an inverted enable signal ENI to Q7 and Q6, respectively. The enable signal generator (18) includes a delay path (30 and 34) for both the EN and ENI signals so that during a low-to-high transition of signal DEC, EN is delayed so that ENI turns Q7 on before EN shuts off Q6. During a high-to-low transition of DEC, ENI is delayed so that Q6 is turned on before Q7 is turned off.