Current sense amplifier
First Claim
1. A current sense amplifier, comprising:
- a voltage comparator having a first input, a second input and an output;
a first clamping device coupled between the first input of the voltage comparator and a first input signal, the first clamping device being coupled to a reference voltage;
a second clamping device coupled between the second input of the voltage comparator and a second input signal, the second clamping device being coupled to the reference voltage; and
a configurable load device coupled between the first and second input of the voltage comparator.
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Abstract
A symmetrical high-speed current sense amplifier having complementary reference cells and configurable load devices that eliminates architecture-related capacitive mismatch contributions. The current sense amplifier is adapted for use in a symmetric sensing architecture and includes a configurable load device. The current sense amplifier includes a voltage comparator, a first clamping device coupled between a first input of the voltage comparator and a first input signal, the first clamping device being coupled to a reference voltage. A second clamping device is coupled between the second input of the voltage comparator and a second input signal the second clamping device being coupled to the reference voltage. The load device may comprise a current mirror that is coupled between the first and second input of the voltage comparator. The current mirror may be configurable by select transistors. Alternatively, the load device may be a hard-wired current mirror, and a multiplexer may be used to select whether the first input signal or the second input signal is connected to a first or second side of the current mirror. Configurable dummy loads may be added at appropriate nodes to optimize the capacitive load and increase the speed of the amplifier. Equalization devices may be coupled between the first and second inputs of the voltage comparator, and between the first input signal and the second input signal.
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Citations
47 Claims
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1. A current sense amplifier, comprising:
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a voltage comparator having a first input, a second input and an output;
a first clamping device coupled between the first input of the voltage comparator and a first input signal, the first clamping device being coupled to a reference voltage;
a second clamping device coupled between the second input of the voltage comparator and a second input signal, the second clamping device being coupled to the reference voltage; and
a configurable load device coupled between the first and second input of the voltage comparator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A current sense amplifier, comprising:
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a voltage comparator having a first input, a second input and an output;
a first clamping device coupled between the first input of the voltage comparator and a first input signal, the first clamping device being coupled to a reference voltage;
a second clamping device coupled between the second input of the voltage comparator and a second input signal, the second clamping device being coupled to the reference voltage;
a load device having a first side and a second side; and
a multiplexer, wherein the multiplexer is adapted to select whether the first input signal or second input signal is connected to the first or second side of the load device. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A memory device, comprising:
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an array of memory cells, the memory cells having a first side and a second side, wherein at least two of the memory cells comprise reference cells;
a plurality of parallel wordlines coupled proximate the first side of the memory cells, the wordlines running in a first direction;
a plurality of parallel bitlines coupled proximate the second side of the memory cells; and
a symmetric sensing circuit including at least one column selector and at least one current sense amplifier, the at least one column selector being coupled to the memory array and comprising at least one column select transistor coupled to each bitline in the array, the at least one current sense amplifier including a voltage comparator, a first clamping device, a second clamping device, and a current mirror having a first side and a second side, wherein the voltage comparator includes a first input, a second input and an output, wherein a first input signal is coupled to the voltage comparator first input, wherein a second input signal is coupled to the voltage comparator second input, the first and second input signals comprising either current from a selected memory cell or current from at least one reference cell, and wherein the voltage comparator outputs a logic state of the selected memory cell. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A method of sensing current, comprising:
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providing a first transistor and a second transistor;
providing a first input signal having a first voltage and a first current;
clamping the first voltage and passing the first current to the first transistor;
providing a second input signal having a second voltage and a second current;
clamping the second voltage and passing the second current to the second transistor, wherein the first input signal and second input signal comprise either current from a selected memory cell or current from at least one reference cell;
selectively mirroring the first or second current from the first or second transistor to the second or first transistor; and
comparing the voltage across the first or second transistor to the voltage across the second or first transistor, wherein selectively mirroring the current amplifies the voltage difference between the voltage across the first transistor and the voltage across the second transistor. - View Dependent Claims (44, 45, 46, 47)
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Specification