Multi-mode Switched Capacitor DC-DC Converter for Compact Implantable Devices
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Solution Overview
Problem
Conventional dc-dc converters often require multiple units to handle different voltage levels for various electrical devices, leading to increased circuit area and cost, and are inefficient when input voltage deviates, as they typically have fixed conversion ratios and cannot adapt to changes in battery voltage in implantable medical devices.
Innovation Solution
A switched capacitor dc-dc converter using only two pump capacitors and three switching phases to produce multiple output voltage levels through selective subcircuit arrangements, allowing for multi-mode operation to maintain desired output voltages as the input voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple conventional dc-dc converters are used to handle different voltage levels, then multiple output voltage levels can be achieved, but circuit area and cost increase
Solution Approach 1:
The patent implements a single dc-dc converter that can operate in multiple conversion modes (first mode with conversion ratio of 0.8, second mode with conversion ratio of 0.6) by selectively configuring the same capacitor and switch components. This multi-functional approach eliminates the need for separate converters for different voltage levels, thereby reducing circuit area while maintaining the ability to provide multiple output voltage levels.
Solution Approach 2:
The converter dynamically switches between different conversion modes by changing the configuration of switches and capacitors based on the required output voltage level. The system can transition between first mode (higher conversion ratio) and second mode (lower conversion ratio) to adapt to different load requirements, providing flexible voltage regulation without requiring multiple fixed-ratio converters.
2Device complexity
If fixed conversion ratio converters are used, then simple circuit design is achieved, but adaptability to input voltage changes is lost
Solution Approach 1:
The converter incorporates dynamic mode switching capability that allows it to adapt to varying input voltage conditions and load requirements. By selectively activating different switch configurations, the converter can adjust its conversion ratio between 0.8 and 0.6, providing adaptability without significantly increasing circuit complexity since the same physical components are reused in different arrangements.
Solution Approach 2:
The system changes its operational parameters (conversion ratio) by reconfiguring the connection topology of the capacitor and switch elements. This allows the converter to optimize its performance for different operating conditions while maintaining a relatively simple underlying circuit structure based on the same hardware components.
3Adaptability or versatility
If multiple pump capacitors are used to achieve multiple conversion ratios, then flexible output voltages are obtained, but component count and circuit area increase
Solution Approach 1:
The patent uses only two pump capacitors (C1 and C2) that serve multiple functions across different conversion modes. The same capacitors are reused in different configurations to achieve both the first conversion ratio (0.8) and the second conversion ratio (0.6), eliminating the need for additional capacitors that would otherwise be required for each separate conversion mode.
Solution Approach 2:
The functionality of multiple capacitors (that would be needed for separate converters or multiple conversion ratios) is merged into just two capacitors through clever topological arrangement. By combining the voltage pumping function for different conversion ratios into the same physical capacitors, the design achieves flexible output voltages with minimal component count.
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 reduces the number of components and circuit area while enabling flexible conversion ratios, allowing a single converter to support multiple output voltage levels and adapt to changes in input voltage, thereby maintaining efficient operation in implantable medical devices.
Implementation Method 1
a switched capacitor dc-dc converter includes one or more capacitors that are selectively switched across an input and output in charge and pump phases to convert the input voltage level to one or more output voltage levels
Data Source
AI summary
The disclosure describes techniques for converting an input voltage level to two or more output voltage levels using only two pump capacitors and three switching phases. The disclosure also describes techniques for selectively controlling a dc-dc converter to operate in different conversion modes. One mode may use only two pump capacitors and three switching phases to produce output voltage levels with a first set of conversion ratios. Another mode may use two pump capacitors and two switching phases to produce output voltage levels with a second set of conversion ratios. The first mode may use three different subcircuit arrangements of the pump capacitors. The second mode may use two different subcircuit arrangements of the pump capacitors. A converter may include switches and pump capacitors that can be selectively configured to transition between two or three different subcircuits, thereby producing output voltages according to different conversion ratios on a selective basis.