Tunable sense amplifier reference for single-ended bit lines
AssigneeKilopass Technology, Inc.
InventorJimmy Lee Reaves
Life of this patent
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Abstract
For a block of memory cells interconnected by single-ended bit lines, a sense amplifier receives the input from a single-ended bit line to determine the logic state of a selected memory cell connected to the single-ended bit line. The sense amplifier also receives a reference voltage generated from a base-emitter voltage of a emitter follower bipolar transistor. The base-emitter voltage is controllably divided by a voltage divider network with selectable resistive elements to tune the reference voltage.
Claims20
A sensing circuit for a plurality of memory cells connected to a bit line in an integrated circuit, the sensing circuit comprising:
- a sense amplifier having a first input connected to the bit line;
- a reference voltage generation circuit having:
- a bipolar transistor having a base, a collector connected to a first voltage supply, and an emitter connected to a second voltage supply;
- a voltage divider network connected between the base and emitter of the bipolar transistor, the voltage divider network including a first circuit branch having a selected impedance and connected between the base of the bipolar transistor and an output terminal, and a second circuit branch having a selected impedance and connected between the output terminal and the emitter of the bipolar transistor, the output terminal connected to a second input of the sense amplifier to provide a tuned reference voltage responsive to the selected impedances of the first and second circuit branches for the sense amplifier;
- whereby the sense amplifier senses the logic state of a memory cell selected from the plurality of memory cells through the bit line with respect to the tuned reference voltage on the output terminal.
In an integrated circuit having a plurality of memory cells and a sense amplifier connected to the memory cells by single bit line, a reference voltage generation circuit providing a reference voltage to the sense amplifier comprising:
- a bipolar transistor having a base, a collector connected to a first voltage supply, and an emitter connected to a second voltage supply;
- and
- a voltage divider network connected between the base and emitter of the bipolar transistor, the voltage divider network including a first circuit branch having a selected impedance and connected between the base of the bipolar transistor and an output terminal, and a second circuit branch having a selected impedance and connected between the output terminal and the emitter of the bipolar transistor, the output terminal connected to a second input of the sense amplifier to provide a tuned reference voltage responsive to the selected impedances of the first and second circuit branches for the sense amplifier;
- whereby the sense amplifier senses the logic state of a selected memory cell through the bit line with respect to the tuned reference voltage on the output terminal.
A method of reading the logic state of a selected memory cell in an integrated circuit, the memory cells connected to a sense amplifier by a single bit line, the method comprising:
- generating a base-emitter voltage from a bipolar transistor having a collector connected to a first voltage supply;
- dividing the base-emitter voltage with a voltage divider network having a first circuit branch having a first selected impedance, and a second circuit branch having a selected second impedance, the first and second circuit branches connected in series across the base-emitter voltage and the first and second selected impedances defining a tuned reference voltage on an output terminal between the first and second circuit branches;
- and
- sensing the voltage on the single bit line with respect to the tuned reference voltage with the sense amplifier;
- whereby the sense amplifier determines the logic state of the selected memory cell.
Dependencies are inferred from the claim text.