Inverting Buck-Boost Converter with Single Inductor and Grounded Switch
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Solution Overview
Problem
Conventional inverting buck-boost regulators require high-side switches, which are inefficient and difficult to fabricate, while Cuk and flyback converters need multiple inductors or transformer windings, increasing size and cost.
Innovation Solution
Implementing an inverting buck-boost topology with a single-inductor boost and charge pump using a grounded switch, allowing for regulated voltage conversion with a single inductor and reducing physical space and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a high-side switch is used in conventional inverting buck-boost regulators, then voltage conversion can be achieved, but manufacturing difficulty increases and efficiency decreases
Solution Approach 1:
The patent inverts the conventional high-side switch configuration by using a low-side grounded switch instead. This inversion allows the use of n-type MOSFETs which are easier to manufacture and more efficient, while still achieving the required inverting buck-boost voltage conversion through the combination of boost and charge pump stages
2Ease of manufacture
If multiple inductors or transformer windings are used in Cuk and flyback converters, then voltage conversion can be achieved, but device size and cost increase
Solution Approach 1:
The patent merges the functions of multiple inductors into a single inductor by combining the boost stage and charge pump stage in a unified topology. This single inductor serves both the boost function and the charge pump function, reducing component count, physical size, and cost while maintaining the inverting buck-boost voltage conversion capability
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
Enables the generation of an inverted output voltage with a magnitude greater or less than the input voltage using a single inductor and a grounded switch, improving efficiency and reducing size compared to conventional regulators.
Implementation Method 1
transferring energy from the input voltage supply to the boost inductor
Implementation Method 2
the charge pump capacitor coupled between the switch node and a pump node
Data Source
AI summary
The disclosed methodology for buck-boost inverted voltage conversion uses a boost stage coupled to a charge pump stage at a switch node controlled by a transistor switch coupled between the switch node and ground. The boost stage includes a boost inductor coupled between an input supply voltage and the switch node, and the charge pump stage includes a charge pump capacitor coupled between the switch node and a pump node which is coupled to the load and an output capacitor in parallel with the load. The regulated inverted output voltage is supplied to the output capacitor and the load by: (a) in a first phase, switching the transistor switch to conducting to couple the switch node to ground, and thereby (i) transferring energy from a source of input voltage source to the boost inductor, and (ii) transferring energy from a charge pump capacitor to the output node, and (b) in the second phase, switching the transistor switch to non-conducting and clamping the charge pump capacitor at a positive reference voltage, and thereby transferring energy from the boost inductor to the charge pump capacitor. In one embodiment, the positive reference voltage is the input voltage (i.e., during the second phase, the charge pump capacitor is clamped to the input voltage).