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:
Nov. 02, 2004
Filed:
Nov. 21, 2002
Takeo Okamoto, Hyogo, JP;
Tetsuichiro Ichiguchi, Hyogo, JP;
Hideki Yonetani, Hyogo, JP;
Tsutomu Nagasawa, Hyogo, JP;
Tadaaki Yamauchi, Hyogo, JP;
Makoto Suwa, Hyogo, JP;
Junko Matsumoto, Hyogo, JP;
Zengcheng Tian, Hyogo, JP;
Renesas Technology Corp., Tokyo, JP;
Abstract
The semiconductor memory device includes a refresh timer for determining a refresh cycle of self-refresh operation. The refresh timer includes a voltage regulator, a ring oscillator and a counter. The voltage regulator generates a bias voltage having positive temperature characteristics. The ring oscillator varies an oscillation cycle of a pulse signal according to the bias voltage. The counter counts a prescribed number of pulse signals and generates a refresh signal for executing refresh operation. The semiconductor memory device thus varies the refresh cycle according to a temperature change, and executes refresh operation with an appropriate refresh cycle.