Multi-Stage Charge Pump Circuit Eliminates Buffering Capacitors
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Solution Overview
Problem
Charge pump circuits used in DC power settings often require additional components like buffering capacitors and have a high number of pins, which can be inefficient, especially in automotive applications where battery voltage may be insufficient for controlling NMOS power switches.
Innovation Solution
A multi-stage charge pump circuit with floating capacitors that eliminates the need for buffering capacitors and reduces the number of pins by using a plurality of switches to control phases for charging capacitors according to specific duty cycles, allowing the output to be approximately 2^N times the input voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional charge pump circuits use buffering capacitors between stages, then voltage stepping is achieved, but the number of pins and circuit complexity increases
Solution Approach 1:
The patent removes the buffering capacitor component from the charge pump circuit between stages. By eliminating this intermediate component, the circuit achieves voltage multiplication through direct capacitive coupling and switched capacitor networks, reducing pin count and overall circuit complexity while maintaining the voltage stepping function
Solution Approach 2:
The patent combines the functions of multiple capacitors and switches into an integrated switched capacitor network. The floating capacitors serve multiple purposes: voltage storage, voltage multiplication, and direct coupling between stages, eliminating the need for separate buffering capacitors and reducing the overall component count
2Reliability
If charge pump circuits use multiple buffering capacitors, then voltage regulation is improved, but the circuit size and component count increase
Solution Approach 1:
The floating capacitors in the patent perform multiple functions simultaneously: they store voltage, multiply voltage through the charge pump action, and provide direct coupling between stages. This multi-functionality eliminates the need for dedicated buffering capacitors, reducing component quantity while maintaining voltage regulation through the coordinated switching network
Solution Approach 2:
The patent employs periodic switching of the capacitor network through controlled duty cycles. The switches periodically charge and discharge the floating capacitors in a coordinated sequence, enabling voltage multiplication and regulation without requiring additional buffering capacitors. The periodic action allows the same capacitors to serve multiple regulatory functions across different time intervals
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
This solution provides a more efficient and compact charge pump circuit capable of stepping up voltage effectively, reducing pin count and eliminating the need for buffering capacitors, making it suitable for automotive applications where battery voltage is insufficient.
Implementation Method 1
multiple stages that each include a floating capacitor
Implementation Method 2
The charge pump circuit may control capacitor charging of each floating capacitor in each stage according to specific duty cycles
Data Source
AI summary
This disclosure describes a charge pump circuit comprising a plurality of switches configured to control phases of the charge pump circuit for charging a first capacitor, a second capacitor and a third capacitor. The phases may include: a first phase that charges the first capacitor to a first voltage based on an input voltage; a second phase that charges the second capacitor to a second voltage based on the first voltage and the input voltage; a third phase that charges the first capacitor to a third voltage based on the input voltage; and a fourth phase that charges the third capacitor to a fourth voltage based the second voltage, the third voltage, and the input voltage. In some examples, one or more of the capacitors are charged with duty cycles that are less than 50 percent.