US 5,399,928 A · Negative voltage generator for flash EPROM design

Abstract

A circuit is provided for supplying a negative high voltage to an integrated circuit from a high positive voltage source V.sub.PP. The negative voltage is applied to a plurality of FLASH electrically erasable programmable read only memory (EPROM) cells. The circuit includes an oscillator coupled to a voltage converter which provides a periodic signal. The periodic signal is coupled to a charge pump including three P-channel type transistors to produce the negative voltage. The source and drain of the first transistor is coupled to the periodic signal. The second transistor's gate and drain is coupled to a reference ground potential with the source coupled to the first transistor's gate. Finally, the third transistor's drain and gate is coupled to the first transistor's gate and the third transistor's source outputs negative voltage to floating gates of the plurality of FLASH EPROM cells during an erase operation. Further, the negative voltage generated is relatively precise, so no regulation is required.

Claims25

Dependent claims

A circuit for supplying a negative voltage to an output node, comprising:

a clock driver, supplying a clock signal having an amplitude corresponding to a first positive voltage;
a positive voltage input, to receive a second positive voltage;
a voltage converter, coupled to the positive voltage input and the clock driver, to convert the clock signal to a positive periodic signal having a particular amplitude different than the first positive voltage;
and
means, coupled to the voltage converter, for generating negative voltage on the output node in response to the positive periodic signal.

2 more elements

Dependencies are inferred from the claim text.

Negative voltage generator for flash EPROM design

Life of this patent

Negative voltage generator for flash EPROM design

Life of this patent

Abstract

Claims25