Transducer Load Impedance Sensing for Charge Pump Voltage Control
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Solution Overview
Problem
Existing audio power amplifier systems in personal devices waste power due to assuming worst-case load impedance scenarios, leading to inefficient power supply voltage generation, especially when the actual load impedance differs from the worst-case assumption.
Innovation Solution
A method and apparatus that detect the load impedance of a transducer device by generating a test analog audio signal and measuring voltage or current responses to determine the impedance, allowing for adaptive control of the charge pump power supply to optimize power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge pump power supply is used with fixed thresholds for worst-case load impedance, then sufficient voltage headroom is ensured to prevent clipping, but power inefficiency occurs when the actual load impedance differs from the worst-case scenario
Solution Approach 1:
The patent applies dynamics by making the charge pump power supply voltage adaptive rather than fixed. The system dynamically adjusts the power supply voltage based on the detected load impedance value, allowing the voltage to vary according to actual operating conditions. This resolves the contradiction by ensuring sufficient voltage headroom only when needed (matching the load impedance requirements) while reducing power consumption when the worst-case scenario does not apply.
Solution Approach 2:
The patent changes the parameter of power supply voltage from a fixed value to a variable value that depends on the detected load impedance. By detecting the actual load impedance and adjusting the charge pump power supply voltage accordingly, the system optimizes the balance between reliability (preventing clipping) and energy efficiency (avoiding excessive voltage when not needed).
2Device complexity
If a linear power amplifier is used for the output stage, then simplicity of design is maintained, but power is wasted during low signal level outputs due to constant voltage drop across the output transistor
Solution Approach 1:
The patent makes the power supply voltage dynamic by linking it to the detected load impedance and signal characteristics. Instead of using a fixed power supply voltage that causes constant power dissipation, the system adjusts the voltage to match the actual requirements of the transducer device and signal level, thereby reducing power waste during low signal level outputs while maintaining design feasibility.
Solution Approach 2:
The patent changes the power supply voltage parameter from constant to variable, where the voltage level is adjusted based on the detected load impedance and operating conditions. This parameter change allows the linear power amplifier to operate more efficiently by reducing the voltage drop across the output transistor when full voltage headroom is not required, thus reducing power dissipation without significantly complicating the design.
3Loss of energy
If Class-G or Class-H amplifier topologies are used to reduce voltage drop across output transistors, then power dissipation is reduced, but the system requires adaptive power supply voltage control based on load impedance
Solution Approach 1:
The patent implements feedback by detecting the load impedance value and using this information to control the charge pump power supply voltage. The system continuously monitors the load impedance and adjusts the power supply voltage accordingly, creating a closed-loop control system that optimizes power efficiency while managing the complexity of adaptive voltage control in Class-G or Class-H amplifier topologies.
Solution Approach 2:
The patent applies self-service by having the system automatically detect its own load impedance and adjust its own power supply voltage without external intervention. The load impedance detection circuit and charge pump power supply work together in an autonomous manner, with the system self-regulating its operating parameters to optimize power efficiency based on actual loading conditions.
Data Source
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AI summary
In accordance with systems and methods of the present disclosure, an audio device may include an electrical terminal, an audio circuit, and a transducer load detection circuit. The electrical terminal may couple a transducer device to the audio device. The audio circuit may generate an analog audio signal, wherein the analog audio signal is coupled to the electrical terminal. The transducer load detection circuit may detect a load impedance of the transducer device when the transducer device is coupled to the audio device from characteristics measured at the electrical terminal.