Voltage Pumping Device Dynamic Source Voltage Control
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Solution Overview
Problem
Conventional voltage pumping devices suffer from instability and peak noise due to over-pumping, especially when the supply voltage level is high, which degrades the device's performance and stability.
Innovation Solution
A voltage pumping device that includes a source voltage generator capable of switching between a first voltage level and a constant second voltage level, with a pumping circuit that adjusts its operation based on the supply voltage level to prevent over-pumping, using a switching device, differential amplifier, or PMOS transistors to manage the voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply voltage level is increased to improve data retention time and reduce self-refresh current, then the back bias voltage can be raised to increase data retention time, but peak noise phenomenon occurs due to over-pumping which degrades device stability
Solution Approach 1:
The voltage pumping device dynamically adjusts the source voltage level based on the supply voltage level. When the supply voltage is high, the source voltage is limited to a predetermined level to prevent over-pumping and peak noise, while still enabling sufficient back bias voltage generation for data retention. This dynamic adaptation resolves the contradiction between reliability and stability.
Solution Approach 2:
The invention changes the operating parameters of the voltage pumping device by introducing a switchable source voltage generator that can operate at different voltage levels. The source voltage is set to a first level (e.g., VDD) under normal conditions and switched to a second predetermined level (e.g., VDD/2) when supply voltage is high, thereby controlling the pumping action to avoid over-pumping while maintaining data retention capability.
2Productivity
If the voltage pumping device operates at high supply voltage levels to improve performance, then more voltage can be pumped for better data retention, but over-pumping occurs which generates peak noise and degrades stability
Solution Approach 1:
The voltage pumping device incorporates a feedback mechanism through the switchable source voltage generator that monitors the supply voltage level and adjusts the source voltage accordingly. When high supply voltage is detected, the system feedbacks by limiting the source voltage to a predetermined level, preventing over-pumping and the generation of peak noise while maintaining adequate pumping capability for data retention.
3Loss of energy
If the source voltage is continuously increased to pump higher voltages for data retention, then the back bias voltage can be increased to reduce off leakage current, but the device becomes unstable due to over-pumping effects
Solution Approach 1:
The invention implements dynamic control of the source voltage level based on operating conditions. The switchable source voltage generator adjusts the source voltage to an appropriate level that enables sufficient back bias voltage pumping to reduce off leakage current, while preventing excessive voltage pumping that would cause instability. This dynamic adjustment optimizes the trade-off between energy loss and stability.
Data Source
AI summary
A voltage pumping device is provided which includes a source voltage generator for generating a source voltage which has a first voltage level for a predetermined period and a second voltage level after a lapse of the predetermined period, the second voltage level being constant, and a pumping circuit configured to receive the source voltage and pump a predetermined voltage.