Cascoded Driver Pre-Charge for Dickson Charge Pump Voltage Stress
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Solution Overview
Problem
Dickson charge pumps experience transient voltage stresses during start-up, which can exceed steady-state voltage stresses, and require a disconnection switch to avoid damaging pump switches, but this adds inefficiency and complexity.
Innovation Solution
A pre-charge circuit with a voltage divider stage and cascoded drivers that charges pump capacitors without the need for a disconnection switch, using a passive or active voltage divider to split the input voltage into multiple levels, allowing drivers to handle voltage differences and charge capacitors efficiently during both pre-charge and steady-state modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a disconnection switch is added to isolate pump switches during pre-charge, then voltage stress on pump switches is reduced, but device complexity and inefficiency increase
Solution Approach 1:
The pre-charge circuit is segmented into multiple voltage levels using a voltage divider network. Each cascoded driver operates at a different voltage level, allowing gradual charging of pump capacitors without exposing pump switches to full input voltage stress during pre-charge.
Solution Approach 2:
Cascoded drivers are introduced as intermediary components between the voltage divider and pump capacitors. These drivers act as voltage-level translators, providing a controlled interface that prevents direct exposure of pump switches to high input voltage during pre-charge operations.
2Productivity
If stacked resistors are used for pre-charge, then pump capacitors can be charged during start-up, but the pre-charge circuit becomes inefficient and requires a disconnection switch
Solution Approach 1:
The circuit transitions between different operational parameters: during pre-charge, the cascoded drivers operate in a linear region providing controlled current charging; during steady-state, they switch to saturation region for efficient switching operation. This parameter change eliminates the need for stacked resistors and disconnection switches.
Solution Approach 2:
The pre-charge circuit is made dynamic through the use of cascoded drivers that can adapt their operation mode. The drivers dynamically adjust their characteristics based on the charging phase, providing efficient operation during both pre-charge and steady-state without requiring separate static components like stacked resistors.
Data Source
AI summary
An apparatus for voltage conversion includes a switched capacitor circuit, a pre-charge circuit, a voltage divider stage, and a driver stage. The switched capacitor circuit has pump capacitors to transfer energy and a steady-state operating mode and a pre-charge mode. The pre-charge circuit initially charges the pump capacitors when the switched capacitor circuit operates in the pre-charge mode. It includes a voltage divider stage having one or more nodes, each of which provides voltage at one of a corresponding one or more voltage levels, and a driver stage having one or more cascoded drivers, each of which comprises a first terminal for receiving a drive signal that depends at least in part on a voltage level at a corresponding one of the nodes, and a second terminal for coupling to a pump capacitor and to another of the drivers.