Five-Level Pulse Modulated Amplifier for Low-EMI Boost Output
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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 vary the output voltage among more than three distinct levels, a monitor to generate control signals based on input voltage, and a feedback system to regulate output voltage, allowing for efficient modulation across five voltage levels with reduced stress and EMI by using a combination of threshold voltages and pulse-density modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the output voltage is modulated in a greater voltage range in boost mode, then the voltage range is increased, but the booster is subject to high voltage and current stresses leading to stress failure
Solution Approach 1:
The patent divides the voltage modulation task into two independent amplification stages: a first amplification stage that provides initial gain and a second amplification stage that provides additional gain. This segmentation allows each stage to operate within manageable voltage ranges, preventing the booster from experiencing excessive stress while achieving the required overall voltage range expansion.
2Adaptability or versatility
If the output voltage is modulated in a greater voltage range in boost mode, then the voltage range is increased, but electro-magnetic interference (EMI) is generated which interferes with other electronic devices
Solution Approach 1:
By segmenting the amplification into two stages, each operating at lower voltage swings, the patent reduces the magnitude of rapid voltage transitions that generate EMI. The first amplification stage operates at lower voltages, and the second stage provides additional gain, collectively achieving the required voltage range with reduced electromagnetic interference compared to a single-stage high-voltage booster.
3Adaptability or versatility
If the output voltage is modulated in a greater voltage range in boost mode, then the voltage range is increased, but power consumption is increased
Solution Approach 1:
The two-stage amplification architecture allows each stage to be optimized for power efficiency at its operating point. The first amplification stage handles the initial voltage range expansion, and the second amplification stage provides additional gain with lower power consumption than a single-stage booster would require to achieve the same overall voltage range.
4Adaptability or versatility
If the output voltage is modulated in a greater voltage range in boost mode, then the voltage range is increased, but quantization error is increased
Solution Approach 1:
By dividing the voltage range expansion into two amplification stages, each stage can apply quantization at intermediate levels rather than requiring a single large quantization step. This segmented approach reduces the quantization error that would result from a single large voltage range expansion, as each stage operates with smaller, more precise voltage steps.
5Adaptability or versatility
If multiple one-bit hysteresis quantizers are used to encode five voltage levels, then the voltage levels are increased, but the complexity of comparator design is increased
Solution Approach 1:
The patent implements a two-stage amplification architecture where each stage can use simpler quantization schemes. The first amplification stage processes the input signal with its own quantization, and the second amplification stage processes the intermediate signal. This segmentation allows each stage to use simpler comparators designed for fewer voltage levels, rather than requiring complex multi-level comparators to handle all five voltage levels simultaneously.
Data Source
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.