Sense amplifier with negative threshold sensing for non-volatile memory
First Claim
1. An apparatus, comprising:
- a discharge transistor;
a first discharge path configured to connect a selected bit line to the discharge transistor;
a second discharge path configured to connect a sense node to the discharge transistor; and
a biasing circuit configured to sense a memory cell connected to the selected bit line by setting a gate voltage on the discharge transistor by a voltage level on the first discharge path, subsequently cutting off the first discharge path while leaving the gate voltage on the discharge transistor to float at the voltage level and discharging the sense node through the discharge transistor by the second discharge path.
1 Assignment
0 Petitions
Accused Products
Abstract
A sense amplifier for a memory circuit that can sense into the deep negative voltage threshold region is described. A selected memory cell is sensed by discharging a source line through the memory cell into the bit line and sense amplifier. While discharging the source line through the memory cell into the sense amplifier, a voltage level on the discharge path is used to set the conductivity of a discharge transistor to a level corresponding to the conductivity of the selected memory cell. A sense node is then discharged through the discharge transistor. To reduce noise, a decoupling capacitor is connected to the control gate of the discharge transistor and an auxiliary keeper current is run through the discharge transistor.
108 Citations
20 Claims
-
1. An apparatus, comprising:
-
a discharge transistor; a first discharge path configured to connect a selected bit line to the discharge transistor; a second discharge path configured to connect a sense node to the discharge transistor; and a biasing circuit configured to sense a memory cell connected to the selected bit line by setting a gate voltage on the discharge transistor by a voltage level on the first discharge path, subsequently cutting off the first discharge path while leaving the gate voltage on the discharge transistor to float at the voltage level and discharging the sense node through the discharge transistor by the second discharge path. - View Dependent Claims (2, 3)
-
-
4. An apparatus, comprising:
-
a transistor; a first switch and a second switch connected in series between a selected memory cell and the transistor, a control gate of the transistor connected to a node between the first switch and second switch, the first switch and second switch configured to discharge the selected memory cell through the transistor when concurrently on and configured to set the control gate of the transistor to float at a voltage level on the node between the first switch and second switch when the first switch and second switches are concurrently off, and a third switch connected between a sense node and the transistor, the third switch configured to discharge the sense node through the transistor with the control gate of the transistor set to float at the voltage level on the node between the first switch and second switch. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method, comprising:
-
discharging a selected memory cell by a first discharge path through a sense amplifier; setting a voltage on a control gate of a discharge transistor to a voltage level along the first discharge path, the voltage level dependent on a data state of the selected memory cell; subsequently providing a supplemental current through the discharge transistor; and while providing the supplemental current through the discharge transistor, discharging a sense node through the discharge transistor with the control gate of the discharge transistor set to the voltage level dependent on the data state of the selected memory cell. - View Dependent Claims (14)
-
-
15. An apparatus, comprising:
-
a first transistor; a first switch connected between a selected memory cell and a gate of the first transistor, the first switch configured to set a voltage level on the gate of the first transistor corresponding to a data state of the selected memory cell; a second switch connected between a sense node and the first transistor and configured to discharge the sense node through the first transistor with the gate of the first transistors set to the voltage level corresponding to the data state of the selected memory cell; and a current source configured to supply a supplemental current through the first transistor subsequent to setting the voltage level on the gate of the first transistor corresponding to the data state of the selected memory cell and prior to discharging the sense node through the first transistor. - View Dependent Claims (16, 17, 18, 19)
-
-
20. A sense amplifier circuit comprising:
-
a transistor connected to a discharge node; means for discharging a selected memory cell through a discharge path of the sense amplifier circuit; means for setting a control gate of the transistor to a voltage level dependent on a data state of the selected memory cell at a node of the discharge path while discharging the selected memory cell; and means for discharging a sense node through the transistor while the control gate of the transistor is set at the voltage level dependent on the data state of the selected memory cell.
-
Specification