Memory Circuit Read Method Using Dual-Voltage Waveform
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Solution Overview
Problem
The existing read operations in memory circuits are prone to read disturb events due to snapback currents generated during the read process, which can alter the resistance state of memory cells and lead to incorrect data retrieval, and they also consume high energy.
Innovation Solution
Implementing a read method that uses two amplitudes of operation voltages during the read operation, where a high-amplitude voltage pulse is applied initially to turn on the selector and a lower-amplitude voltage is maintained to reduce snapback voltage and current, thereby minimizing the probability of read disturb events and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-amplitude voltage is applied during read operation to turn on the selector, then the selector can be properly activated, but snapback current increases causing read disturb events and high energy consumption
Solution Approach 1:
The patent applies periodic voltage pulses with different amplitudes during the read operation. A first voltage pulse with higher amplitude is applied initially to turn on the selector, followed by a second voltage pulse with lower amplitude to maintain the on-state. This periodic action with varying amplitudes reduces snapback current while ensuring proper selector activation, thereby resolving the contradiction between reliability and harmful snapback current effects.
2Speed
If a single high-amplitude voltage is used for read operation, then the read speed is fast, but energy consumption increases due to sustained high voltage application
Solution Approach 1:
The patent uses periodic voltage pulses where a first high-amplitude pulse quickly turns on the selector (maintaining fast read speed), followed by a second lower-amplitude pulse that maintains the on-state with reduced energy consumption. This temporal separation of voltage amplitudes achieves both fast read operation and reduced energy usage.
Solution Approach 2:
The patent dynamically adjusts the voltage amplitude during the read operation based on the operational phase. The voltage waveform transitions from a higher amplitude during the turn-on phase to a lower amplitude during the maintain phase, optimizing both speed and energy consumption through dynamic voltage control.
3Reliability
If voltage threshold is exceeded to ensure proper selector turn-on, then selector activation is reliable, but read disturb events occur due to excessive voltage
Solution Approach 1:
The patent applies a first voltage pulse that exceeds the threshold to reliably turn on the selector, then follows with a second voltage pulse at or below the threshold to maintain the on-state without causing read disturb events. This periodic application of differently-amplitued pulses resolves the contradiction between reliable turn-on and prevention of harmful read disturb effects.
Data Source
AI summary
A read method and a write method for a memory circuit are provided, wherein the memory circuit includes a memory cell and a selector electrically coupled to the memory cell. The read method includes applying a first voltage to the selector, wherein a first voltage level of the first voltage is larger than a voltage threshold corresponding to the selector; and applying, after the applying of the first voltage, a second voltage to the selector to sense one or more bit values stored in the memory cell, wherein a second voltage level of the second voltage is constant and smaller than the voltage threshold, wherein a first duration of the applying of the first voltage is smaller than a second duration of the applying of the second voltage, wherein the second voltage is applied following the end of the first duration.