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US 7,002,371 B2Granted
Level shifter
AssigneeFreescale Semiconductor, Inc.
InventorsKiyoshi Kase, May Len, Dzung T. Tran
Life of this patent
Estimating the term…
Abstract
A level shifter with cross coupled inverters having different threshold voltages. The output of the level shifter is pulled to a known voltage state during power up. In some examples, one of the inverters includes an additional N-channel transistor wherein the threshold voltage is greater the threshold voltage of the other inverter due to the additional transistor.
Claims41
A level shifter comprising:
- a first inverter having a first threshold voltage;
- and
- a second inverter having a second threshold voltage, the second threshold voltage being greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- the first inverter has a first configuration of transistors and the second inverter has a second configuration of transistors;
- the second configuration includes an additional transistor not found in the first configuration;
- wherein the predetermined amount is at least one fourth or greater of a gate-to-source voltage of the additional transistor.
3 more elements
A level shifter comprising:
- a first inverter having a first threshold voltage;
- and
- a second inverter having a second threshold voltage, the second threshold voltage being greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- a transistor have a gate coupled to an input of the level shifter and a current terminal;
- a stress reduction transistor having a first current terminal coupled to the current terminal of the transistor and a second current terminal coupled to an output of the first inverter or an output of the second inverter.
2 more elements
A level shifter comprising:
- a first inverter having a first threshold voltage;
- and
- a second inverter having a second threshold voltage, the second threshold voltage being greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- a third transistor including a current terminal coupled to an output of the first inverter or an output of the second inverter, the third transistor including a gate coupled to an input of the level shifter;
- a fourth transistor including a current terminal coupled to the output of the first inverter or an output of the second inverter, the fourth transistor including a gate;
- a third inverter having an input coupled to the input of the third transistor and an output coupled to the gate of the fourth transistor;
- wherein the third inverter includes a transistor having a current terminal, wherein the current terminal is coupled to a first voltage source;
- wherein the first inverter includes a first transistor having a current terminal coupled to a second voltage source;
- wherein the second inverter includes a second transistor having a current terminal coupled to the second voltage source;
- wherein the second voltage source powers up before the first voltage source.
7 more elements
A level shifter comprising:
- a first inverter having a first threshold voltage;
- and
- a second inverter having a second threshold voltage, the second threshold voltage being greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- the first inverter has a first configuration of transistors and the second inverter has a second configuration of transistors;
- the first configuration includes an additional transistor not found in the second configuration.
2 more elements
A level shifter comprising:
- a first inverter having a first threshold voltage;
- and
- a second inverter having a second threshold voltage, the second threshold voltage being greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- the first inverter includes a first transistor of a first channel type;
- the second inverter includes a second transistor of the first channel type;
- wherein the first transistor has a gate dielectric of a different thickness than a gate dielectric of the second transistor.
3 more elements
A level shifter comprising:
- a first inverter having a first threshold voltage;
- and
- a second inverter having a second threshold voltage, the second threshold voltage being greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- the first inverter has a first transistor configuration with a first transistor;
- the second inverter has a second transistor configuration with a second transistor corresponding to the first transistor of the first transistor configuration;
- the first transistor has a strength different from a strength of the second transistor by at least a predetermined amount.
3 more elements
A method of making a level shifter comprising:
- providing a first inverter having a first threshold voltage;
- and
- providing a second inverter having a second threshold voltage greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- wherein the first inverter has first configuration of transistors
- wherein the second inverter has a second configuration of transistors,
- wherein the second configuration includes an additional transistor not found in the first configuration;
- wherein the predetermined amount is at least one-fourth or greater of a gate-to-source voltage of the additional transistor.
4 more elements
A method of making a level shifter comprising:
- providing a first inverter having a first threshold voltage;
- and
- providing a second inverter having a second threshold voltage greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- wherein the first inverter has a first configuration of transistors
- wherein the second inverter has a second configuration of transistors,
- wherein the second configuration includes an additional transistor not found in the first configuration;
- wherein the additional transistor includes a drain and a gate, the gate being connected to the drain.
4 more elements
A method of making a level shifter comprising:
- providing a first inverter having a first threshold voltage;
- and
- providing a second inverter having a second threshold voltage greater than the first threshold voltage by at least a predetermined amount, wherein the first inverter and the second inverter are cross-coupled;
- the first inverter has a first configuration of transistors;
- the second inverter has a second configuration of transistors;
- wherein the first configuration includes an additional transistor not found in the second configuration.
3 more elements
A level shifter comprising:
- a first inverter having a first configuration of transistors;
- a second inverter having a second configuration of transistors;
- wherein the first inverter and the second inverter are cross coupled;
- wherein the second configuration includes an additional transistor not found in the first configuration;
- wherein the additional transistor includes a drain and a gate, wherein the gate is connected to the drain.
2 more elements
Dependencies are inferred from the claim text.