Internal Voltage Generator Leakage Current Control
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Solution Overview
Problem
Conventional internal voltage generating circuits in semiconductor memory devices face issues with leakage current, leading to unstable core voltage levels and increased stress on internal circuits, particularly as external power supply voltages decrease, causing the core voltage to exceed target levels and potentially shortening the lifetime of the internal circuit.
Innovation Solution
An internal voltage generating circuit with a current sinking unit that adjusts and discharges excess leakage current to ground, maintaining a constant internal voltage level by controlling the sinking leakage current, even with variations in external power supply voltage and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If external power supply voltage is decreased to enable sub-micron level memory devices to operate at high frequency, then operational frequency is improved, but leakage current increases causing internal voltage to exceed target levels
Solution Approach 1:
The patent implements a feedback mechanism where the internal voltage generating circuit continuously monitors the core voltage level and adjusts its output accordingly. When leakage current causes the core voltage to rise above the target level, the feedback signal reduces the voltage generation, thereby maintaining voltage stability despite high-frequency operation and leakage current variations.
Solution Approach 2:
The patent dynamically adjusts electrical parameters including voltage levels and current sinking rates based on operating conditions. By changing these parameters in response to leakage current variations and temperature changes, the circuit maintains stable internal voltage while operating at high frequencies with decreased external power supply voltage.
2Speed
If external power supply voltage is decreased for high frequency operation, then operational frequency is improved, but stress on internal circuits increases potentially shortening lifetime
Solution Approach 1:
The patent applies beforehand cushioning by implementing protective measures before excessive voltage can damage internal circuits. The current sinking unit and feedback mechanism proactively prevent voltage from rising to harmful levels, cushioning the internal circuits against stress and potential damage that would otherwise occur during high-frequency operation with decreased external voltage.
3Device complexity
If conventional internal voltage generating circuit is used without current sinking unit, then device complexity is reduced, but internal voltage stability deteriorates due to leakage current
Solution Approach 1:
The patent extracts and addresses the leakage current problem by separating the voltage generation function from the current management function. The current sinking unit is extracted as a distinct functional block that specifically handles leakage current, allowing the main voltage generating circuit to focus on voltage production while the sinking unit maintains voltage stability by removing excess current.
Data Source
AI summary
An internal voltage generating circuit includes an internal voltage generating unit configured to generate an internal voltage that corresponds to a target voltage level by driving an internal voltage terminal with an external power supply voltage, and current sinking unit configured to adjust leakage current introduced to the internal voltage terminal in response to the external power supply voltage.