Supply-Compensated Amplifier Circuit for Gain and Distortion Control
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Solution Overview
Problem
Amplifier circuits face distortion and gain errors due to variations in supply voltage, which existing loop filter technologies struggle to fully compensate for, leading to suboptimal output signal quality.
Innovation Solution
The implementation of a feedback path, loop filter circuitry, and encoder circuitry that modulates the power supply voltage and generates a drive signal to compensate for supply-dependent gain variations, using analog and digital converters and pulse width modulation to ensure consistent output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the amplifier circuit modulates the supply voltage to generate the output signal, then the amplifier can operate efficiently with high power conversion, but variations in supply voltage cause gain errors and distortion in the output signal
Solution Approach 1:
The patent implements a feedback mechanism where the output signal is fed back through feedback circuitry to the input stage. This closed-loop feedback allows the system to automatically correct for supply voltage variations by comparing the actual output with the expected output and adjusting the modulation accordingly, thereby maintaining accurate gain and reducing distortion while preserving high power efficiency
Solution Approach 2:
The patent dynamically adjusts modulation parameters based on supply voltage conditions. The modulation circuitry changes its operating parameters in response to supply voltage variations, allowing the amplifier to maintain consistent output accuracy across different supply conditions while continuing to operate in high-efficiency modulation mode
2Reliability
If existing loop filter technologies are used to compensate for supply voltage variations, then some gain error correction is achieved, but distortion and gain errors are not fully eliminated
Solution Approach 1:
The patent divides the compensation function into separate specialized circuit blocks: feedback circuitry for detecting output errors, compensation circuitry for generating correction signals, and modulation circuitry for applying corrections. This segmented architecture allows each block to be optimized for its specific function, achieving superior distortion reduction and gain stability compared to conventional integrated loop filters
Solution Approach 2:
The patent introduces an intermediate compensation signal path that processes supply voltage variation information separately before combining it with the main audio signal. This intermediary processing allows for precise correction of distortion and gain errors without interfering with the primary signal path, achieving better linearity and lower distortion
3Adaptability or versatility
If the supply voltage varies due to battery discharge or load connection, then the amplifier adapts to available power, but the gain of the output stage changes causing distortion
Solution Approach 1:
The patent implements dynamic tracking of supply voltage variations through the feedback mechanism. As supply voltage changes due to battery discharge or load conditions, the feedback circuit continuously monitors the resulting output changes and dynamically adjusts the modulation depth and timing to maintain constant gain, allowing the amplifier to adapt to varying supply conditions without sacrificing output fidelity
Data Source
AI summary
Amplifier circuitry comprising: output stage circuitry configured to modulate a power supply voltage, based on a drive signal received at an input of the output stage circuitry, to generate an amplifier output signal; a feedback path coupled to an output of the output stage circuitry and configured to generate a feedback signal based on the amplifier output signal; loop filter circuitry configured to receive an input signal based on the feedback signal and to output a digital loop filter output signal; divider circuitry configured to divide the digital loop filter output signal by the power supply voltage to generate a divided digital output signal; and encoder circuitry configured to generate the drive signal based on the divided digital output signal.