High voltage NMOS pass gate having supply range, area, and speed advantages
First Claim
1. A high voltage pass gate, comprising:
- first and second coupling capacitors each having upper and lower plates;
a plurality of transistors, each transistor having a corresponding gate, source, and drain, wherein the plurality of transistors comprises;
first, second, and third series boost transistors;
first and second isolation boost transistors;
wherein the first series boost transistor source, the second isolation boost transistor gate, the second series boost transistor gate, and the second coupling capacitor lower plate are coupled;
wherein the second series boost transistor source, the first isolation boost transistor gate, the first series boost transistor gate, the third series boost transistor gate, and the first coupling capacitor lower plate are coupled;
wherein the first isolation boost transistor source, first series boost transistor drain, and the third series boost transistor drain are coupled;
wherein the second isolation boost transistor source and the second series boost transistor drain are coupled;
wherein the first isolation boost transistor drain and the second isolation boost transistor drain are coupled to a high voltage control node; and
wherein the first coupling capacitor upper terminal is coupled to a first clock input, and the second coupling capacitor upper terminal is coupled to a second clock input.
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Accused Products
Abstract
According to an aspect of the embodiments, the block decoder control circuits which drive the pass transistors for the word lines for a flash memory array are driven with a control voltage that is regulated to be one enhancement transistors threshold voltage higher than the highest voltage that is actually driven onto the word lines. According to another aspect of some of the embodiments, the block decoder control circuits are implemented with transistors having a very low threshold voltage. According to yet another aspect of some of the embodiments, a special series connection is used to prevent any leakage current through the block decoder control circuit from the high voltage generating charge pumps which might otherwise result from the use of low threshold voltage transistors. In the special series connection, any leakage current occurs from the supply voltage source rather than from the high voltage generating charge pumps. According to still another aspect of some of the embodiments, a special gate connection applies an intermediate bias voltage higher than a positive supply voltage onto the gates of the unselected block decoder transistors that are connected to a high-voltage. Several embodiments are presented which combine the regulated control voltage aspect and various combinations of the other aspects.
22 Citations
40 Claims
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1. A high voltage pass gate, comprising:
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first and second coupling capacitors each having upper and lower plates; a plurality of transistors, each transistor having a corresponding gate, source, and drain, wherein the plurality of transistors comprises; first, second, and third series boost transistors; first and second isolation boost transistors; wherein the first series boost transistor source, the second isolation boost transistor gate, the second series boost transistor gate, and the second coupling capacitor lower plate are coupled; wherein the second series boost transistor source, the first isolation boost transistor gate, the first series boost transistor gate, the third series boost transistor gate, and the first coupling capacitor lower plate are coupled; wherein the first isolation boost transistor source, first series boost transistor drain, and the third series boost transistor drain are coupled; wherein the second isolation boost transistor source and the second series boost transistor drain are coupled; wherein the first isolation boost transistor drain and the second isolation boost transistor drain are coupled to a high voltage control node; and wherein the first coupling capacitor upper terminal is coupled to a first clock input, and the second coupling capacitor upper terminal is coupled to a second clock input. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A high voltage pass gate, comprising:
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first, second, third, and fourth coupling capacitors each having upper and lower plates; a plurality of transistors, each transistor having a corresponding gate, source, and drain, wherein the plurality of transistors comprises; first, second, and third series boost transistors; first and second isolation boost transistors; wherein the first series boost transistor source, the second series boost transistor gate, and the fourth coupling capacitor lower plate are coupled; wherein the second series boost transistor source, the first series boost transistor gate, the third series boost transistor gate, and the second coupling capacitor lower plate are coupled; wherein the first isolation boost transistor source, the first series boost transistor drain, the third series boost transistor drain, the second isolation boost transistor gate, and the third coupling capacitor lower terminal are coupled; wherein the second isolation boost transistor source, the second series boost transistor drain, the first isolation boost transistor gate, and the first coupling capacitor lower terminal are coupled; wherein the first isolation boost transistor drain and the second isolation boost transistor drain are coupled to a high voltage control node; and wherein the first coupling capacitor upper terminal and second coupling capacitor upper terminal are coupled to a first clock input, and the second coupling capacitor upper terminal and the fourth coupling capacitor upper terminal are coupled to a second clock input. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A high voltage pass gate, comprising:
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first, second, third, and fourth coupling capacitors each having upper and lower plates; a plurality of transistors, each transistor having a corresponding gate, source, and drain, wherein the plurality of transistors comprises; first, second, and third series boost transistors; first and second isolation boost transistors; first and second decoupling boost transistors; wherein the first series boost transistor source, the second isolation boost transistor gate, the second series boost transistor gate, and the fourth coupling capacitor lower plate are coupled; wherein the second series boost transistor source, the first isolation boost transistor gate, the first series boost transistor gate, the third series boost transistor gate, and the second coupling capacitor lower plate are coupled; wherein the first isolation boost transistor source, first series boost transistor drain, the third series boost transistor drain, the second decoupling boost transistor gate, and the third coupling capacitor lower plate are coupled; wherein the second isolation boost transistor source, the second series boost transistor drain, the first decoupling boost transistor gate, and the first coupling capacitor lower plate are coupled; wherein the first decoupling boost transistor source and the second isolation boost transistor drain are coupled; wherein the second decoupling boost transistor source and the second isolation boost transistor drain are coupled; wherein the first isolation boost transistor drain and the second isolation boost transistor drain are coupled to a high voltage control node; and wherein the first and second coupling capacitor upper terminals are coupled to a first clock input, and the third and fourth coupling capacitor upper terminals are coupled to a second clock input. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A high voltage pass gate, comprising:
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first, second, third, and fourth coupling capacitors each having upper and lower plates; a plurality of transistors, each transistor having a corresponding gate, source, and drain, wherein the plurality of transistors comprises; first, second, and third series boost transistors; first and second isolation boost transistors; first and second decoupling boost transistors; wherein the first series boost transistor source, the second isolation boost transistor gate, the second series boost transistor gate, and the fourth coupling capacitor lower plate are coupled; wherein the second series boost transistor source, the first isolation boost transistor gate, the first series boost transistor gate, the third series boost transistor gate, and the second coupling capacitor lower plate are coupled; wherein the first isolation boost transistor source, and the first series boost transistor drain, and the third series boost transistor drain are coupled; wherein the second isolation boost transistor source and the second series boost transistor drain are coupled; wherein the first decoupling boost transistor source, the first isolation boost transistor drain, and the second decoupling boost transistor gate are coupled; wherein the second decoupling boost transistor source, the second isolation boost transistor drain, and the first decoupling boost transistor gate are coupled; wherein the first isolation boost transistor drain and the second isolation boost transistor drain are coupled to a high voltage control node; and wherein the first and second coupling capacitor upper terminals are coupled to a first clock input, and the third and fourth coupling capacitor upper terminals are coupled to a second clock input. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification