Internal Voltage Detection Circuit for DRAM Temperature Compensation
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Solution Overview
Problem
Dynamic random access memory (DRAM) cells experience inadequate charge sharing and data misrecognition at low temperatures due to increased threshold voltage, leading to incorrect read and write operations, while high temperatures result in off-leakage current and reduced refresh time, causing reliability issues.
Innovation Solution
An internal voltage detection circuit and device that adjust the back bias voltage (VBB) based on operating temperature, raising it at low temperatures to prevent data misrecognition and lowering it at high temperatures to reduce off-leakage current, with a clamp mechanism to maintain voltage levels and prevent charge loss at excessive temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cell transistor operates at high temperature, then the off-leakage current and reverse drift current increase, but the refresh time decreases leading to data loss
Solution Approach 1:
The patent changes the threshold voltage parameter by applying back-bias voltage to suppress off-leakage current and reverse drift current at high temperatures. This increases the refresh time and prevents data loss by reducing the rate of charge leakage from the storage capacitor
2Device complexity
If a fixed threshold voltage is used, then the circuit design is simple, but the DRAM fails to operate reliably across different temperatures
Solution Approach 1:
The patent transforms the static threshold voltage into a dynamic parameter by introducing a back-bias voltage control circuit. This circuit automatically adjusts the threshold voltage based on operating conditions, enabling the DRAM to adapt to different temperatures while maintaining reliable operation
Solution Approach 2:
The patent implements a feedback mechanism where the back-bias voltage is adjusted based on the operating state of the cell transistor. This feedback control ensures that the threshold voltage is optimally maintained across different temperatures, improving reliability without excessive complexity
Data Source
AI summary
An internal voltage detection circuit and an internal voltage generation device using the same are disclosed. The internal voltage detection circuit includes a first detect signal generator for generating a first detect signal to detect a level of an internal voltage corresponding to an operating temperature of a memory cell, a second detect signal generator for generating a second detect signal to detect a specific level of the internal voltage corresponding to a preset temperature, and a detect signal clamp unit for comparing a level of the first detect signal and a level of the second detect signal with each other and clamping the first detect signal according to a result of the comparison.