Programming voltage generator circuit for programmable memory
Patent 5175706 Issued on December 29, 1992. Estimated Expiration Date: 
May 23, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
May 23, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesWaveform generating apparatus Patent #: 4447747 InventorAssigneeApplicationNo. 707255 filed on 05/23/1991US Classes:365/226, POWERING327/105, Synthesizer365/45, ANALOG STORAGE SYSTEMS365/227Conservation of powerExaminersPrimary: Fears, Terrell W.Foreign Patent References
International ClassG11C 017/00Foreign Application Priority Data1989-12-07 FRAbstractElectrically programmable memories often include an internal circuit for establishing a programming voltage Vpp higher than the supply voltage. This circuit is formed by a charge pump followed by a voltage regulator. Previously, an analog circuit was usually provided behind the regulator to convert the level of voltage Vpp, set up by the charge pump, into a signal with a slow-rising edge (to reduce the constraints on the programmed cells and increase their lifetime). Instead of such analog circuit, the present invention provides a digital control circuit to control the regulator to set up a regulation voltage that rises gradually from a low value up to the desired value Vpp. The digital control circuit comprises counter with k outputs which enables the gradual short-circuiting and unshort-circuiting of the various series-mounted transistors constituting the regulator, thus making the regulation voltage increase slowly.Other References
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