Charge Pump Stage Protection via Trimmable Discharge
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Solution Overview
Problem
Multi-stage charge pumps used in memory devices retain capacitive charge when inactive, which can stress and damage low-voltage components, particularly due to uncontrolled voltage differences across dielectric layers, posing a risk to device reliability and lifespan.
Innovation Solution
Incorporating a trimmable current source as a discharge device to safely bleed off remaining charge from disabled stages, ensuring voltages across low-voltage devices remain below their threshold, thereby protecting them from damage and maintaining reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low-voltage devices are used in charge pump stages to improve performance and efficiency, then speed and conductivity are enhanced, but the devices become vulnerable to damage from retained capacitive charge when the charge pump is inactive
Solution Approach 1:
A discharge device is introduced as an intermediary component between the capacitive element and ground. This discharge device remains non-conductive during normal operation but becomes conductive when the charge pump is inactive, providing a safe discharge path for retained charge. The discharge device acts as a mediator that protects the low-voltage device from voltage spikes without interfering with normal charge pump operation.
Solution Approach 2:
The discharge device is configured to activate automatically when the charge pump transitions to an inactive state, performing the protective discharge action before the retained charge can cause damage. This preliminary protective action ensures that vulnerable low-voltage devices are protected from voltage stress before failure can occur.
2Power
If multiple low-voltage stages are connected in series to generate high-voltage output, then the desired voltage multiplication is achieved, but each stage retains capacitive charge that can damage the thin dielectric layers of low-voltage devices
Solution Approach 1:
The charge pump is divided into multiple independent stages, each with its own capacitive element and discharge device. This segmentation allows each stage to be independently protected by its own discharge device, ensuring that retained charge in one stage cannot damage devices in other stages. Each stage can be safely discharged without affecting the operation of other stages.
Solution Approach 2:
Individual discharge devices are introduced as intermediary protective components for each stage's capacitive element. These discharge devices provide dedicated protection paths for each stage, preventing voltage stress from propagating to low-voltage devices while maintaining the high-voltage generation capability of the multi-stage configuration.
3Loss of energy
If the charge pump is disabled to save energy, then power consumption is reduced, but retained charge on capacitive elements continues to stress dielectric layers and reduce device lifespan
Solution Approach 1:
The discharge device is configured to automatically activate when the charge pump is disabled, providing self-service protection without requiring external control. The discharge device monitors the operational state and autonomously discharges retained charge, extending device lifespan without adding complex control circuitry or increasing power consumption during normal operation.
Solution Approach 2:
The harmful retained charge that causes dielectric stress is converted into a controlled discharge event that benefits device reliability. By providing a controlled discharge path, the system transforms the potentially damaging retained charge into a harmless discharge process that actually extends the lifespan of low-voltage devices by preventing uncontrolled voltage stress.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the risk of damage to low-voltage components by controlling voltage differences, allowing for the use of low-voltage devices in high-voltage applications while maintaining performance and efficiency without increasing the size or complexity of the charge pump.
Implementation Method 1
individual stages may retain capacitive charge even when the charge pump and/or stage are not active
Implementation Method 2
a trimmable current source to selectively discharge the capacitive charge of disabled stages
Data Source
AI summary
Apparatus, systems, and methods are disclosed, including a high-voltage charge pump including multiple pump stages connected in series to provide a high-voltage output, a common discharge circuit, and multiple high-voltage devices coupled between the outputs of each of the multiple pump stages and the common discharge circuit. Each of the multiple pump stages include a low-voltage switching device. The common discharge circuit is coupled to each of the multiple pump stages and is configured to discharge the multiple pump stages when the multiple pump stages are disabled. The multiple high-voltage devices include a respective high-voltage device coupled between an output of each of the multiple pump stages and the common discharge circuit.