Vth-Cancellation Charge Pump Reverse Leakage Prevention
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Solution Overview
Problem
Charge pumps with VTH-cancellation architecture face reverse leakage issues when delivering high currents, leading to increased power loss and slow recovery time due to reverse leakage, which hampers their efficiency and dynamic performance.
Innovation Solution
The introduction of shorting transistors and diodes or switches between nodes and control gates in the charge pump circuit to prevent reverse leakage, ensuring that switches are properly turned off during high current delivery, thereby reducing power loss and improving recovery time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If VTH-cancellation architecture is used to improve power efficiency and IV characteristics, then power efficiency is improved, but reverse leakage increases leading to slower recovery time
Solution Approach 1:
A body diode is introduced as an intermediary component between the output transistor and the pump capacitor. This diode acts as a mediator that allows controlled reverse leakage current to flow during the transfer phase while preventing unwanted reverse current during the output phase, thus resolving the contradiction between maintaining power efficiency and reducing recovery time loss
Solution Approach 2:
The invention changes the operational parameters of the output transistor by controlling its gate voltage through the offset cancellation section. By dynamically adjusting the gate voltage based on the clock phase, the transistor's conductivity is optimized to minimize reverse leakage while maintaining efficient power transfer, thus improving both power efficiency and recovery time
2Power
If VTH-cancellation pumps deliver very high currents, then current delivery capability is improved, but reverse leakage hampers recovery and causes power loss
Solution Approach 1:
The invention converts the harmful reverse leakage effect into a beneficial feature by intentionally designing the output transistor and body diode configuration to utilize reverse leakage in a controlled manner. The body diode's reverse leakage is harnessed to maintain proper voltage levels during switching transitions, transforming what was previously a power loss mechanism into a feature that supports high current delivery while minimizing net energy loss
Data Source
AI summary
Techniques are presented to reduce reversion leakage in charge pump circuits. The exemplary circuit is a charge pump of the voltage doubler type, where the output of each leg is supplied through a corresponding output transistor. An auxiliary charge pump is used to supply the gates of the output transistors in order to cancel the threshold voltage of these output transistors. To reduce reverse leakage back through the output transistors, in each leg of the charge pump a switch is connected between the gate of the output transistor and the output level of the leg so the these levels can be shorted when that particular is not supplying the pump's output.