Write Amplifier Power Circuit for Semiconductor Memory
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Solution Overview
Problem
In semiconductor memory devices, successive write operations lead to excessive boosting of bit line voltage due to the use of a higher power supply voltage, which disrupts the correct reference level and causes erroneous operations, particularly in precharge operations, affecting high-speed processing and power efficiency.
Innovation Solution
Implementing a write amplifier power generating circuit that controls the power supply voltage by switching between a first voltage during write overdrive and a second voltage after amplification is complete, ensuring the bit line voltage does not exceed the internal voltage VDL, thereby preventing excessive boosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a higher power supply voltage (VEXT) is used for write operations to achieve high-speed processing, then write speed is improved, but bit line voltage becomes excessively boosted disrupting reference levels
Solution Approach 1:
The power supply voltage for the write amplifier is dynamically switched between two levels: VEXT (higher voltage) during the write overdrive period to achieve high-speed writing, and VDL (lower internal voltage) after amplification completes to prevent excessive bit line voltage boosting. This dynamic voltage adjustment resolves the contradiction by adapting the voltage level to the operational phase.
Solution Approach 2:
The write amplifier operates in periodic cycles with distinct phases: an overdrive period using VEXT for rapid writing, followed by a normal period using VDL for stable operation. The control signal switches the power supply voltage periodically according to the write operation status, ensuring high speed when needed and reference level stability when the overdrive phase ends.
2Productivity
If overdrive write method is used to achieve high-speed processing, then productivity is improved, but bit line voltage excessive boosting causes erroneous operations
Solution Approach 1:
The harmful effect of excessive voltage boosting is isolated to a specific time period (the overdrive phase). By extracting the high-voltage operation to only the necessary overdrive period and switching to low-voltage operation afterward, the patent eliminates the harmful effect while preserving the beneficial high-speed writing capability.
Solution Approach 2:
The write amplifier rushes through the write operation at high voltage (VEXT) during the overdrive period to complete the writing quickly, then immediately switches to low voltage (VDL) to skip the excessive voltage boosting phase. This rushing through the critical write phase at high speed followed by immediate voltage reduction resolves the contradiction between productivity and harmful voltage effects.
Data Source
AI summary
A write amplifier power generating circuit includes a control unit for changing an output voltage. In a first write cycle in which a pair of bit lines are being amplified, a write operation is performed by an overdrive write method in which a high level from a write amplifier is set to a first voltage (for example, a power supply voltage). In a second write cycle after amplification in the pair of the bit lines has been completed, a write operation is performed by a write method in which the high level from the write amplifier is set to a second voltage (for example, an internal voltage).