Level-Aware Bias Voltage Generator for Reliable Memory Programming
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Solution Overview
Problem
Existing level shifters in non-volatile memory devices have a narrow voltage operating range and fail to function reliably during voltage ramp-up periods, leading to potential mis-programming of memory cells.
Innovation Solution
A level-aware bias voltage generator is introduced, utilizing cascoded bias voltages generated by voltage dividers and level shifters to maintain stable transistor operation across a wider voltage range, ensuring reliable programming by adjusting bias voltages for both P-type and N-type transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing level shifters are used to provide high programming voltage, then the voltage can be generated, but the voltage operating range is narrow and reliability is poor during voltage ramp-up period
Solution Approach 1:
The patent implements dynamic bias voltage adjustment by detecting the power supply voltage level and selectively applying different bias voltages to transistor gates. The bias voltage generator circuit monitors the power supply voltage and dynamically adjusts the bias voltage applied to the level shifter transistors, enabling the circuit to adapt to varying voltage conditions including the voltage ramp-up period, thereby expanding the operational voltage range and improving reliability.
Solution Approach 2:
The patent changes the operating parameters of the level shifter by adjusting the bias voltage applied to transistor gates based on the power supply voltage level. During voltage ramp-up, a specific bias voltage is applied to ensure proper transistor operation, while under normal conditions, the bias voltage is adjusted accordingly. This parameter adjustment allows the level shifter to operate reliably across a wider voltage range.
2Productivity
If high programming voltage is provided during voltage ramp-up, then programming can be performed, but mis-programming may occur due to unstable transistor operation
Solution Approach 1:
The patent applies preliminary action by preparing the transistor operating conditions before the actual programming operation. The bias voltage generator circuit detects the power supply voltage level in advance and adjusts the transistor gate bias voltages accordingly before the programming voltage is applied. This preliminary adjustment ensures that transistors are in the correct operating state, preventing mis-programming and ensuring reliable programming operations.
Solution Approach 2:
The patent implements feedback by having the bias voltage generator circuit continuously monitor the power supply voltage level and adjust the transistor bias voltages accordingly. The circuit detects the actual voltage conditions and provides appropriate bias adjustment to maintain stable transistor operation, thereby ensuring programming accuracy and preventing mis-programming events.
Data Source
AI summary
The present disclosure provides a semiconductor device and a bias voltage generator. The semiconductor device includes a voltage divider, a voltage selection circuit, and a level shifter. The voltage divider is configured to divide a power supply voltage to generate a first bias voltage. The voltage selection circuit is configured to select between the first bias voltage and a reference voltage to output a second bias voltage. The level shifter is configured to adjust a voltage level of the power supply voltage using the first bias voltage and the second bias voltage.