Push-Pull Wave-Shaping Amplifier for Load-Independent ZVS
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Solution Overview
Problem
Existing switched-mode power amplifiers, such as Class E and Class F amplifiers, face limitations in high-frequency operations due to high peak voltages, output capacitance, and inefficiencies, particularly in Class E/F converters, which require improvements in design topology and performance.
Innovation Solution
A push-pull fast-switching amplifier design with multiple signal-amplification circuit stages operating out of phase, utilizing a waveform-shaping circuit and LC-based impedance paths to reduce peak-switch voltages, achieve resistive-load independent ZVS operation, and minimize circulating energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Class E amplifier topology is used to achieve zero-voltage switching operation, then switching losses are reduced and efficiency is improved, but peak voltage across the switch increases to about 3.6 times the DC input voltage
Solution Approach 1:
The patent divides the single high-voltage Class E amplifier into two lower-voltage Class E amplifiers operating in push-pull configuration. Each amplifier handles half of the total output power, with their outputs combined through a combining network. This segmentation reduces the peak voltage stress on each switching device while maintaining the zero-voltage switching benefit for reduced switching losses.
Solution Approach 2:
The patent merges the outputs of two Class E amplifiers through a combining network to achieve the desired output power. The combining network integrates the power from both amplifiers while managing the voltage and current waveforms to maintain efficiency and reduce stress on individual components.
2Stability of the object's composition
If Class F amplifier topology is used with multiple-resonator output filters to control harmonic content, then drain voltage waveform is improved to square wave and current to half sine wave, but output capacitance limits open-impedance tuning at high frequencies
Solution Approach 1:
The patent segments the harmonic control function across multiple resonators in each Class E amplifier stage, allowing independent tuning of fundamental and harmonic frequencies. This segmentation enables effective waveform control at high frequencies by distributing the filtering function across multiple frequency-selective elements rather than requiring a single complex filter.
3Loss of energy
If Class E/F combined topology is used to achieve high voltage and high-frequency power conversion, then efficiency is improved and device voltage stress is reduced, but design complexity increases and load-independent ZVS operation becomes difficult to maintain
Solution Approach 1:
The patent applies local quality by optimizing each Class E amplifier stage independently with its own resonant circuit parameters tuned for specific frequency and load conditions. The push-pull configuration allows each side to be designed and tuned separately, simplifying the overall design process while maintaining load-independent zero-voltage switching through local compensation networks.
Data Source
AI summary
In certain examples, methods and semiconductor structures are directed to circuit-based apparatus in which an amplifier includes stacked, first and second circuit amplification stages to operate out of phase from one another for providing a push-pull operation, with each of the first and second circuit stages including a switching circuit and an impedance path to drive the switching circuit. The apparatus further includes a waveform-shaping circuit to shape, in response to each of the first and second circuit stages, a voltage signal for presentation to the switching circuit. As may be implemented in various more-specific examples, the apparatus may generate a constant output voltage with high efficiency across a wide range of resistive loads.