Flash Memory Word Line Driver with Variable Capacitance Clamp
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Solution Overview
Problem
Conventional read voltage generators in flash memory devices on System-on-Chip (SoC) fail to maintain a constant read voltage level due to power and temperature fluctuations, leading to increased power consumption and potential incorrect readings during the read mode, as they require a setting time greater than 50 ns, which is not satisfied by the flash memory access time.
Innovation Solution
A word line driving circuit that uses a read voltage generator with a level detector and charge sharing clamp circuit to precharge a clamp capacitor, adjusting its capacitance in response to power supply voltage fluctuations, ensuring a stable read voltage is generated and distributed to the word line, reducing power consumption by rapidly operating in standby mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional read voltage generator is used to maintain a constant read voltage level, then the voltage stability is improved, but the setting time exceeds 200 ns which is greater than the flash memory access time requirement
Solution Approach 1:
The clamp capacitor is precharged during the standby mode before the read operation begins. This preliminary action allows the read voltage to be ready immediately when the read command is issued, eliminating the need for lengthy setting time during the actual read operation and satisfying the flash memory access time requirement.
Solution Approach 2:
The circuit dynamically adjusts the capacitance of the clamp capacitor based on the detected power supply voltage level. By changing the capacitance value in response to voltage fluctuations, the circuit maintains a substantially constant read voltage while enabling faster response time compared to conventional fixed-capacitance designs.
2Speed
If the read voltage generator operates during standby mode to generate read voltage in advance, then the read voltage is ready for quick access, but the power consumption during standby mode increases
Solution Approach 1:
Instead of continuously operating the read voltage generator during standby mode, the circuit operates periodically - only when a read command is detected. The clamp capacitor retains its precharged voltage between operations, providing fast read voltage generation on demand while minimizing power consumption during idle standby periods.
Solution Approach 2:
The clamp capacitor serves itself by retaining the precharged voltage automatically without requiring continuous power supply or active control during standby mode. When a read command occurs, the stored charge is immediately available to provide the required read voltage, eliminating the need for continuous operation and reducing standby power consumption.
3Stability of the object's composition
If the capacitance of the clamp capacitor is changed to compensate for power supply voltage fluctuations, then the read voltage stability is improved, but the circuit complexity increases
Solution Approach 1:
The circuit uses a level detector to monitor the power supply voltage level and provides feedback control for adjusting the clamp capacitor's capacitance. By changing the capacitance in response to detected voltage fluctuations, the circuit automatically compensates for power supply variations and maintains a substantially constant read voltage.
Solution Approach 2:
The circuit changes the physical parameter of capacitance of the clamp capacitor to compensate for power supply voltage fluctuations. By adjusting the capacitance value based on the detected voltage level, the circuit maintains a substantially constant read voltage without requiring complex voltage regulation circuitry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables rapid operation of word lines with reduced power consumption in standby mode, maintaining a constant read voltage level despite power supply fluctuations, thus improving the accuracy and efficiency of read operations in flash memory devices.
Implementation Method 1
a read voltage generator configured to precharge a clamp capacitor with a power supply voltage in response to a read command to stably generate a read voltage in which a capacitance of the clamp capacitor is changed so that to compensate for a fluctuation of a power supply voltage
Implementation Method 2
a level detector configured to detect a fluctuation of the power supply voltage level to generate a level detecting signal in response to the read command
Implementation Method 3
a word line driver configured to distribute electric charges precharged in the clamp capacitor to a word line in response to a word line selecting signal
Data Source
AI summary
A word line driving circuit includes a read voltage generator and a word line driver. The read voltage generator precharges a clamp capacitor with a power supply voltage to stably generate a read voltage in response to a read command. A capacitance of the clamp capacitor is varied to compensate for a fluctuation of a power supply voltage level. The word line driver distributes electric charges precharged in the clamp capacitor to a word line in response to a word line selecting signal. Therefore, the word line driving circuit reduces unnecessary power consumption in a standby mode by operating the word line rapidly with charge sharing in a read mode.