SINGLE POWER SUPPLY LEVEL SHIFTER
First Claim
1. A single power supply level shifter for a semiconductor device having first and second power supply voltage domains, the level shifter comprising:
- a first inverter inverting an input signal from the first voltage domain and providing a first inverted signal in the second voltage domain;
a second inverter inverting the first inverted signal and providing an output signal in the second voltage domain;
a capacitor element; and
a charging control circuit charging the capacitor element towards the second voltage when the input signal is high, and conducting a discharge current from the capacitor element during a transition of the input signal from high to low, wherein the discharge current accelerates a corresponding transition of the first inverted signal from low to high.
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Abstract
A single power supply level shifter has first and second inverters in tandem that invert an input signal from a first voltage domain and provide a first inverted signal and an output signal in a second voltage domain. A charging control circuit charges a capacitor towards the second voltage when the input signal is high, and conducts a discharge current from the capacitor during a transition of the input signal from high to low to accelerate a corresponding transition of the first inverted signal from low to high. A third inverter controls a current reduction transistor in series with the first inverter, and a third control transistor connected between the input and the charging control circuit to accelerate the flow of discharge current during the transition of the input signal from high to low.
5 Citations
12 Claims
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1. A single power supply level shifter for a semiconductor device having first and second power supply voltage domains, the level shifter comprising:
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a first inverter inverting an input signal from the first voltage domain and providing a first inverted signal in the second voltage domain; a second inverter inverting the first inverted signal and providing an output signal in the second voltage domain; a capacitor element; and a charging control circuit charging the capacitor element towards the second voltage when the input signal is high, and conducting a discharge current from the capacitor element during a transition of the input signal from high to low, wherein the discharge current accelerates a corresponding transition of the first inverted signal from low to high. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A level shifter for converting an input signal from a first domain at a first power supply voltage to an output signal for a second domain at a second power supply voltage, the level shifter comprising:
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a first inverter having a first output connected in series between first and second power supply terminals in the second domain to invert the input signal and provide a first inverted signal; a second inverter having a second output connected in series between the first and second power supply terminals in the second domain to invert the first inverted signal and provide the output signal; a current reduction transistor having a control terminal, and a current conduction path connected in series between the first output and the first power supply terminal; a third inverter having a third output connected in series between the first and second power supply terminals in the second domain to invert the first inverted signal and provide a third inverted signal on the control terminal to reduce the current in the current reduction transistor and the first inverter when the first inverted signal is low; a capacitor; and a charging control circuit having a first control transistor having a control terminal connected to the first output and a current conduction path connected to the third output for charging the capacitor towards the second voltage when the input signal is high, and a second control transistor having a control terminal connected to the third output and a current conduction path connected to the first output for conducting a discharge current from the capacitor during a transition of the input signal and the third inverted signal from high to low, wherein the discharge current accelerates a corresponding transition of the first inverted signal from low to high. - View Dependent Claims (9, 10, 11, 12)
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Specification