Waveform generating apparatus Patent #: 4447747
ApplicationNo. 707255 filed on 05/23/1991
US Classes:365/226, POWERING327/105, Synthesizer365/45, ANALOG STORAGE SYSTEMS365/227Conservation of power
ExaminersPrimary: Fears, Terrell W.
Foreign Patent References
International ClassG11C 017/00
Foreign Application Priority Data1989-12-07 FR
AbstractElectrically 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.