Configurable Amplifier Output Stage Calibration for Seamless Mode Switching
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Solution Overview
Problem
Existing audio amplifiers, particularly class-D amplifiers, face challenges in efficiently switching between Class-AB and Class-D output stages, leading to audio artifacts due to differences in gain and offset between the modes.
Innovation Solution
An amplifier with a configurable final output stage and a calibration subsystem that includes a modulator and output switches, along with a signal feedback network, allows for decoupling and recalibration of parameters to compensate for offset and gain differences between the Class-AB and Class-D modes, reducing audio artifacts by maintaining consistent signal characteristics across modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If switching between Class-AB and Class-D output stages is implemented to improve power efficiency and dynamic range, then power efficiency and dynamic range performance are improved, but audio artifacts occur due to gain and offset differences between modes
Solution Approach 1:
The calibration subsystem performs preliminary calibration of the output stage before switching between Class-AB and Class-D modes. By pre-adjusting gain and offset parameters and storing calibration data, the system ensures seamless transitions without audio artifacts, resolving the contradiction between mode-switching capability and audio quality.
Solution Approach 2:
The calibration subsystem uses feedback mechanisms to detect and compensate for gain and offset differences between Class-AB and Class-D modes. By continuously monitoring output characteristics and adjusting parameters based on feedback signals, the system maintains audio quality while enabling efficient mode switching.
2Adaptability or versatility
If a configurable final output stage is implemented to allow switching between Class-AB and Class-D modes, then adaptability and performance are improved, but device complexity increases due to additional calibration subsystem
Solution Approach 1:
The calibration subsystem is designed with multi-functionality to handle both Class-AB and Class-D mode calibrations using a single integrated structure. By making the calibration subsystem universal rather than mode-specific, the patent reduces overall device complexity while maintaining adaptability across different output stages.
Solution Approach 2:
The system manages complexity by dynamically changing operational parameters (gain, offset, calibration mode) rather than requiring separate hardware paths for each mode. This parameter-based approach allows a single configurable output stage to handle multiple modes without proportionally increasing device complexity.
3Loss of energy
If class-D amplifier is used to improve power efficiency, then power dissipation is reduced, but quiescent power consumption increases when amplifying low-magnitude signals
Solution Approach 1:
The amplifier implements dynamic switching between Class-AB and Class-D modes based on signal characteristics. For low-magnitude signals, the system dynamically selects Class-AB mode to minimize quiescent power consumption, while switching to Class-D mode for higher signals to reduce power dissipation, thus resolving the energy trade-off.
Solution Approach 2:
The system changes operational parameters (amplification mode, gain settings) based on signal magnitude to optimize power consumption. By adjusting parameters dynamically rather than operating in a fixed mode, the amplifier achieves low quiescent power for small signals while maintaining efficient power dissipation characteristics.
Data Source
AI summary
A method for offset calibration may include decoupling a modulator input of a first path from a first stage output, coupling a second path output to the modulator input, applying a common-mode voltage to a second path input, receiving a calibration signal from the modulator output generated in response to the common-mode voltage, and modifying one or more parameters of the modulator to compensate for an offset between the first path and the second path indicated by the calibration signal. A method for gain calibration may include decoupling a modulator input from a first stage output, decoupling a second path from the first stage output, applying a first test signal to the modulator input, applying a second test signal to a second path input, wherein the second test signal is of opposite phase as the first test signal, coupling a second path output to an amplifier input via a calibration feedback network, receiving a calibration signal from the first stage output generated in response to the first test signal and the second test signal, and modifying one or more parameters of the second path to compensate for a difference in respective gains of the modulator and the second path indicated by the calibration signal.