Multi-Level PWM Amplifier With One-Bit Quantizer for Low-EMI Boost Mode
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Solution Overview
Problem
Conventional Class D amplifiers face challenges in achieving high power efficiency, reducing component stress, minimizing electromagnetic interference (EMI), and lowering quantization error when operating in boost mode, which requires modulation across a greater voltage range, leading to increased complexity and potential stress failure.
Innovation Solution
The amplifier system incorporates a power stage with inputs for three supply voltages, a controller to generate control signals for varying the output voltage among more than three distinct levels, a monitor to provide control signals based on the input voltage, and a feedback system to adjust the output voltage, allowing for efficient modulation between +V PP, +V DD, GND, -V DD, and -V PP, with pulse-modulated signals having small amplitude and reduced EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output voltage is modulated in a greater voltage range in boost mode, then the power output capability is improved, but the voltage and current stresses on the booster increase leading to higher probability of stress failure
Solution Approach 1:
The voltage boosting function is segmented from the power output stage. The booster only needs to provide voltage elevation, while separate switching elements (first and second switching elements) handle the power delivery to the load. This segmentation allows the booster to operate at lower stress levels while still achieving high power output capability through the coordinated action of multiple components.
Solution Approach 2:
The patent introduces intermediate switching elements that act as mediators between the booster and the load. These switching elements buffer the stress on the booster by handling the high-current power delivery, allowing the booster to focus solely on voltage elevation without承受ing the full burden of high power stress.
2Power
If the output voltage is modulated in a greater voltage range in boost mode, then the voltage boosting capability is improved, but the electromagnetic interference generation increases
Solution Approach 1:
The patent employs periodic switching action where the switching elements operate in controlled on/off cycles. This periodic operation allows for pulse-width modulation that achieves voltage boosting while the controlled duty cycles and timing reduce electromagnetic interference compared to continuous high-voltage switching. The periodic nature allows energy to be delivered in controlled bursts rather than continuous high-stress operation.
3Adaptability or versatility
If the output voltage is modulated in a greater voltage range in boost mode, then the voltage range coverage is improved, but the power consumption increases
Solution Approach 1:
The patent changes operational parameters dynamically by switching between different voltage levels (first voltage level from the booster and second voltage level without the booster) based on the required output. This parameter switching allows the system to achieve wide voltage range coverage while consuming power efficiently by selecting the appropriate voltage source for each operating condition rather than continuously operating the power-consuming booster at maximum capacity.
4Adaptability or versatility
If the output voltage is modulated in a greater voltage range in boost mode, then the output voltage range is improved, but the quantization error increases
Solution Approach 1:
The voltage range is segmented into multiple discrete levels that can be selectively applied. By dividing the overall voltage range into distinct quantized levels (first voltage level and second voltage level), the system achieves wide output voltage range coverage while maintaining precise control at each level. This segmentation approach reduces quantization error compared to attempting to cover the entire range with a single continuous adjustment mechanism.
Data Source
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AI summary
An amplifier system may include a power stage having inputs for three different supply voltages and an output for coupling to a load, a controller to generate control signals to the power stage that cause the power stage to vary an output voltage applied to the load among more than three distinct voltage levels, a monitor to provide a first control signal to the controller based on an input voltage signal, and a feedback system to provide a second control signal to the controller based on comparison of the output voltage and the input signal.