Inverting Switching Regulator Using Flying Capacitor
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Solution Overview
Problem
Conventional inverting switching regulators for generating negative supply voltages require devices with high breakdown voltages, leading to low efficiency, large area occupation, and difficulties in integration due to high parasitic components and large voltage swings.
Innovation Solution
An inverting switching regulator design that uses an inductor and a flying capacitor, with a method involving two phases to generate a negative output voltage from a positive input voltage, limiting voltage swing and enabling high efficiency and compact integration by using switches with low breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If devices with high breakdown voltages are used to generate large voltage swing, then the negative supply voltage can be generated, but the efficiency decreases due to high parasitic components
Solution Approach 1:
The voltage conversion function is segmented into two distinct phases: a first phase where the flying capacitor is charged by the positive input voltage, and a second phase where the flying capacitor is connected in series with the ground node and inductor to generate negative voltage. This segmentation allows the use of low breakdown voltage devices in each phase while achieving high voltage swing overall.
Solution Approach 2:
The circuit operates by periodically switching between the first phase and second phase through the plurality of switches. During the first phase, the flying capacitor charges; during the second phase, it discharges to generate negative voltage. This periodic action enables continuous negative supply voltage generation using devices that cannot withstand the full voltage swing simultaneously.
2Reliability
If devices with high breakdown voltages are used, then large voltage swing can be handled, but the area occupied increases
Solution Approach 1:
By segmenting the operation into two phases with different circuit configurations, the patent enables the use of smaller, lower breakdown voltage devices. The flying capacitor and inductor share the voltage stress in different phases, reducing the required device size and total area occupation.
3Reliability
If devices with high breakdown voltages are used, then large voltage swing is achieved, but integration with other devices becomes difficult
Solution Approach 1:
The segmented two-phase operation simplifies integration by allowing standard low-voltage devices to be used throughout the circuit. Each device only needs to handle the voltage present during its active phase, not the full voltage swing, making co-integration with other standard devices feasible.
4Reliability
If conventional inverting switching regulator is used, then negative supply voltage is generated, but parasitic components increase
Solution Approach 1:
The patent segments the voltage conversion process into two phases, where the flying capacitor is charged during the first phase and discharged during the second phase. This segmentation reduces the voltage stress on individual components during each phase, thereby reducing parasitic effects such as capacitive leakage and resistive losses.
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
The solution achieves high efficiency and reduced area occupation, allowing for the integration of the inverting switching regulator with other devices, and provides a continuous output delivery current with reduced ripple, enabling the use of smaller components.
Implementation Method 1
a flying capacitor coupled to the second terminal of the inductor. The switches are configured to apply a negative voltage to the second terminal of the inductor by charging the flying capacitor by the positive input voltage during a first phase, and by connecting the flying capacitor in series to a ground node and the inductor during a second phase.
Implementation Method 2
an inductor configured to pass an inductor current from a first terminal to a second terminal of the inductor
Data Source
AI summary
An inverting switching regulator is provided. The inverting switching regulator is used to generate a negative output voltage based on a positive input voltage. The inverting switching regulator includes an inductor configured to pass an inductor current from a first terminal to a second terminal; a flying capacitor coupled to the second terminal of the inductor; and a plurality of switches configured to apply a negative voltage to the second terminal of the inductor by charging the flying capacitor by the positive input voltage during a first phase, and by connecting the flying capacitor in series to a ground node and the inductor during a second phase.