Sensing scheme for the semiconductor memory
First Claim
1. A semiconductor memory sensing scheme in a memory array, comprising:
- a memory array with memory cells, that generates a first voltage output and a second voltage output when the memory cell is accessed, wherein the first voltage output ramps from a predetermined voltage level to a higher voltage level, and the second voltage output keeps in a predetermined voltage level;
a first N-type device coupled between ground and one corresponding bit line of the memory array, wherein discharging the bit line voltage when memory array accessing is completed;
a second N-type device coupled between ground and one corresponding bit line-bar of the memory array, wherein discharging the bit line voltage when memory array accessing is completed; and
a differential amplifier with two input nodes coupled to the bit line and the bit line-bar of the memory array to generate a first sense output voltage if the first voltage output of one memory cell is higher than a second voltage output of the one memory cell and to generate a second sense output voltage if the first voltage output of one memory cell is lower than a second voltage output of the one memory cell.
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Abstract
The present invention provides a sensing scheme for semiconductor memory. N-type devices coupling between ground and a bit line and a bit line-bar of memory cells quickly discharge a bit line and a bit line-bar during non-accessing mode. During data accessing mode, one P-type device of an SRAM memory cell pulls up bit line or bit line-bar node slowly to minimize the inductive coupling noise and VDD, Ground bouncing, hence allows smaller amount of differential voltage input to the sense amplifier and results in lower power consumption. A self-timer counts the needed time and sends a signal to enable the current driven sense amplifier and to turn off the word line to avoid further pulling up the bit line or bit line-bar voltage and to reduce the power dissipation.
20 Citations
14 Claims
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1. A semiconductor memory sensing scheme in a memory array, comprising:
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a memory array with memory cells, that generates a first voltage output and a second voltage output when the memory cell is accessed, wherein the first voltage output ramps from a predetermined voltage level to a higher voltage level, and the second voltage output keeps in a predetermined voltage level; a first N-type device coupled between ground and one corresponding bit line of the memory array, wherein discharging the bit line voltage when memory array accessing is completed; a second N-type device coupled between ground and one corresponding bit line-bar of the memory array, wherein discharging the bit line voltage when memory array accessing is completed; and a differential amplifier with two input nodes coupled to the bit line and the bit line-bar of the memory array to generate a first sense output voltage if the first voltage output of one memory cell is higher than a second voltage output of the one memory cell and to generate a second sense output voltage if the first voltage output of one memory cell is lower than a second voltage output of the one memory cell. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A control circuit for a semiconductor memory array, comprising:
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a sense amplifier for amplifying output from a memory cell; and a self-timer coupled to the sense amplifier for counting a time and sending out control signals to shut off the sense amplifier according to the time and pulling down a word line to avoid further current sinking through the memory cell; and a delay device for controlling a second time to discharge a bit line and a bit line-bar of the memory array. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification