SLEW RATE CONTROLLED LEVEL SHIFTER WITH REDUCED QUIESCENT CURRENT
First Claim
1. A slew rate controlled level shifter circuit for selectively passing a first voltage level from a first voltage source to an output node when an input data signal has a first value, for selectively passing a second voltage level from a second voltage source to the output node when the input data signal has a second value, wherein the level shifter circuit comprises:
- a first current path including a first current mirror transistor coupled between the first voltage source and a first node, a first switch transistor coupled between the first node and a second node, and a first slew rate control transistor coupled between the second node and the second voltage source;
a second current path including a second current mirror transistor coupled between the first voltage source and a third node, a third current mirror transistor coupled between the third node and the output node, a second switch transistor coupled between the output node and a fourth node, and a second slew rate control transistor coupled between the fourth node and the second voltage source,wherein gate terminals of the first and second slew rate control transistors are coupled to a fifth node,wherein gate terminals of the first and second current mirror transistors are connected to the third node, and a gate terminal of the third current mirror transistor is connected to the first node, andwherein gate terminals of the first and second switch transistors respectively receive differential control signals.
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Accused Products
Abstract
A level shifter circuit includes two parallel current paths respectively controlled by switch transistors, a Wilson current mirror circuit, and a slew rate control circuit to selectively couple an output node either to a high (first) voltage source or to a ground (second voltage) source in response to differential input control signals signal. When the output node reaches a stable (high or low) voltage level, the low voltage on one of the current paths turns off a Wilson current mirror transistor in the other current path, thereby preventing quiescent current during stable periods. An optional cascode transistor is added to facilitate fabrication using low threshold voltage transistors.
173 Citations
13 Claims
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1. A slew rate controlled level shifter circuit for selectively passing a first voltage level from a first voltage source to an output node when an input data signal has a first value, for selectively passing a second voltage level from a second voltage source to the output node when the input data signal has a second value, wherein the level shifter circuit comprises:
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a first current path including a first current mirror transistor coupled between the first voltage source and a first node, a first switch transistor coupled between the first node and a second node, and a first slew rate control transistor coupled between the second node and the second voltage source; a second current path including a second current mirror transistor coupled between the first voltage source and a third node, a third current mirror transistor coupled between the third node and the output node, a second switch transistor coupled between the output node and a fourth node, and a second slew rate control transistor coupled between the fourth node and the second voltage source, wherein gate terminals of the first and second slew rate control transistors are coupled to a fifth node, wherein gate terminals of the first and second current mirror transistors are connected to the third node, and a gate terminal of the third current mirror transistor is connected to the first node, and wherein gate terminals of the first and second switch transistors respectively receive differential control signals. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A slew rate controlled level shifter circuit for selectively generating a first voltage level on an output node when an input data signal has a first value, for selectively generating a second voltage level on the output node when the input data signal has a second value, and for controlling transitions between the first and second voltage levels in accordance with a selected slew rate determined by a slew rate current source, wherein the level shifter circuit comprises:
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a first current path including a first switch transistor and a first slew rate control transistor connected in series between a first node and the second voltage source, wherein the first switch transistor is controlled by the input data signal such that the first switch transistor is opened when the input data signal has the first value, and is closed when the input data signal has the second value; and a second current path including a second switch transistor and a second slew rate control transistor connected in series between the output node and the second voltage source1 wherein the second switch transistor is controlled by the input data signal such that the second switch transistor is opened when the input data signal has the second value, and is closed when the input data signal has the first value; and a Wilson current mirror circuit connected to the first and second current paths. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A level shifter circuit for selectively coupling, in response to a data signal, an output node to a first voltage level provided by a first voltage source and a second voltage level provided by a second voltage source such that transitions between the first and second voltage levels are controlled in response to a selected slew rate determined by a slew current source, the level shifter circuit comprising:
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a first current mirror including a first current mirror transistor connected between the first voltage source and a first node, a second current mirror transistor connected between the first voltage source and a third node, and a third current mirror transistor connected between the third node and the output node, wherein gate terminals of the first and second current mirror transistors are connected to the third node, and a gate terminal of the third current mirror transistor is connected to the first node; a slew rate control circuit including a first slew rate control transistor connected between the second voltage source and a second node, a second slew rate control transistor connected between the second voltage source and a fourth node, and a third slew rate transistor connected between the second voltage source and a fifth node wherein gate terminals of the first, second and third slew rate control transistors are coupled to the fifth node, and wherein the fifth node is coupled to the slew current source; a first switch transistor connected between the first node and the second node; and a second switch transistor connected between the fourth node and the output node; wherein the at least one data signal is applied to the gate terminals of the first and second switch transistors.
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Specification