Coupled Class-D LC DC-DC Converter Without External Passives
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Solution Overview
Problem
Conventional DC-DC converters face challenges in efficiently regulating power and reducing switching losses while maintaining high power density and efficiency, especially under varying load conditions.
Innovation Solution
The proposed electrical converter employs two self-oscillating class-D LC oscillators connected in series or parallel, with inductive and capacitive coupling, allowing for high-frequency operation and quasi-adiabatic switching, eliminating the need for external passive components and reducing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional DC-DC converter topologies (buck, boost, switched capacitor) are used with switching stages and LC filters, then power regulation is achieved, but switching losses increase and power density decreases
Solution Approach 1:
The patent replaces conventional mechanical switching stages and LC filters with a fully integrated switched-capacitor network operating in the GHz range. The mechanical analog switches are replaced by transistor-based switching elements integrated directly into the capacitor network, eliminating the need for separate switching stages and external passive components. This substitution reduces switching losses and enables higher power density through integration.
Solution Approach 2:
The patent implements a nested structure where oscillators are completely internalized within the switched-capacitor network. The oscillator circuitry is embedded within the capacitor switching network itself, with no external clock generation required. This nesting eliminates external components and reduces overall system complexity while maintaining power regulation functionality.
2Productivity
If switching frequency is increased to improve power density, then power delivery efficiency improves, but switching losses increase
Solution Approach 1:
The patent employs periodic oscillating action at GHz frequencies through self-oscillating circuits embedded in the switched-capacitor network. The oscillators generate periodic voltage and current waveforms that naturally drive the capacitor switching at optimal frequencies. This periodic action enables high power delivery efficiency while the self-oscillating mechanism automatically adjusts frequency to minimize switching losses under varying load conditions.
Solution Approach 2:
The patent implements dynamic operation where the switching frequency and conversion ratio can vary continuously based on load conditions. The self-oscillating circuitry automatically adjusts the operating frequency and voltage conversion ratio in real-time, enabling the converter to operate at optimal efficiency points across different power levels from 70 µW to 0.5 W without fixed frequency constraints.
3Reliability
If external passive components (inductors, capacitors) are used for filtering and power storage, then power regulation is improved, but device complexity and area increase
Solution Approach 1:
The patent merges multiple functions into the switched-capacitor network: power conversion, filtering, energy storage, and oscillation generation are all integrated within the same capacitor network. The flying capacitors serve both as power conversion elements and as filtering components, eliminating the need for separate external inductors and capacitors. This merging reduces device complexity and external component requirements while maintaining reliable power regulation.
Solution Approach 2:
The switched-capacitor network performs multiple functions simultaneously: voltage conversion, current regulation, power filtering, and oscillation generation. The same capacitive elements that enable voltage transformation also provide the necessary filtering and energy storage functions, making the circuit universally functional without requiring dedicated components for each function.
4Speed
If converter operates at high frequencies (GHz range) to improve power density, then power delivery speed improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves GHz-range operation by changing the fundamental operating parameters of the converter. The switched-capacitor network is designed to operate at frequencies 100-1000 times higher than conventional converters (GHz instead of MHz), which fundamentally alters the timing and duration of switching operations. This parameter change enables high-speed power delivery while the integrated design maintains manufacturing feasibility through standardized transistor and capacitor geometries optimized for high-frequency operation.
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 configuration achieves high power density, efficient power delivery, and reduced switching losses, enabling GHz-range frequencies and peak efficiencies from 70 uW to 0.5 W with minimal output ripple and no external load capacitor, while maintaining high power density.
Implementation Method 1
the one or more coupling elements comprise inductive coupling elements, coupling oscillating currents of the at least two oscillators, in particular wherein one or more of the inductive coupling elements are transformers
Implementation Method 2
the one or more coupling elements comprise capacitive coupling elements, coupling oscillating voltages of the at least two oscillators, in particular wherein one or more of the capacitive coupling elements are capacitors
Implementation Method 3
In embodiments, the oscillators are self-oscillating oscillators. The oscillators being self-oscillating means that the oscillator oscillates if a supply voltage is connected to the oscillator, without any external periodic signal being required to maintain the oscillation. In embodiments, the oscillators are negative gm oscillators.
Data Source
AI summary
A DC-DC converter topology based on electromagnetically coupled class-D LC oscillator is proposed. An electrical converter comprises at least two oscillators (1,2), each of the at least two oscillators being designed to have an oscillating current and an oscillating voltage. Coupling elements (16, 17, 18, 19) arranged to couple the oscillating currents of the at least two oscillators and/or the oscillating voltages of the at least two oscillator. The at least two oscillators are connected in a series connection, adding their oscillating voltages, and/or in a parallel connection, adding their oscillating currents. The topology can be fully integrated, that is, it can be realized as an integrated circuit without external components, in particular without external passive components, such as capacitors and/or inductors.