Sigma-Delta Amplifier Feedback Switching for Mismatch Error Suppression
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Solution Overview
Problem
Sigma-delta modulators in amplifiers face efficiency reduction and require large-scale LC filters due to low output power and mismatch errors between feedback components caused by manufacturing processes, which is not suitable for thin, light, and power-saving electronic devices.
Innovation Solution
An amplifier circuit with a sigma-delta modulating circuit, power stage circuit, error suppressing circuit, and selecting circuit that generates and adjusts output voltages to suppress mismatch errors between feedback components, allowing for efficient operation without the need for large-scale LC filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-bit quantizer is adopted in the sigma-delta modulator, then the circuit complexity is reduced, but the amplifier efficiency is reduced and a large-scale LC filter is required
Solution Approach 1:
The patent introduces a dynamic element matching (DEM) mechanism that dynamically switches between different feedback paths based on the quantizer output state. When the output is at extreme levels (±1), one feedback path is activated; when at intermediate levels, another path is activated. This dynamic switching optimizes the feedback component utilization, improving amplifier efficiency while maintaining the simple one-bit quantizer structure.
Solution Approach 2:
The patent changes the operational parameters of the feedback components by introducing multiple feedback paths with different characteristics. By selectively activating different feedback paths based on the quantizer output state, the effective feedback parameter is dynamically adjusted, allowing the system to achieve better efficiency without requiring complex filtering.
2Measurement precision
If feedback components are used in the amplifier, then the accuracy is improved, but manufacturing process variations cause mismatch errors between feedback components
Solution Approach 1:
The patent intentionally introduces asymmetric feedback paths with different characteristics to compensate for manufacturing mismatches. By designing the feedback paths to have complementary asymmetries, the system can cancel out the errors caused by manufacturing variations in individual components, thereby maintaining high accuracy despite process variations.
Solution Approach 2:
The patent employs a feedback mechanism that monitors the output and adjusts the feedback signal accordingly. By using multiple feedback paths with different characteristics and selectively activating them based on the operating state, the system can compensate for mismatch errors and maintain accurate feedback control despite manufacturing variations.
3Reliability
If a large-scale LC filter is added to solve the output signal issue, then the signal quality is improved, but the device size increases and space is consumed
Solution Approach 1:
The patent extracts and eliminates the need for large-scale LC filtering by using dynamic element matching to directly control the feedback paths. The DEM mechanism processes the signal in the time domain, converting the filtering requirement into a temporal switching problem that can be solved with simple switches and capacitors, thereby removing the bulky LC filter while maintaining signal quality.
Solution Approach 2:
The patent replaces the mechanical/physical LC filter system with an electronic switching system. Instead of using large inductors and capacitors to filter the signal, the system uses rapid electronic switching of feedback paths to achieve the same filtering effect in the time domain, dramatically reducing the physical size and space requirements.
Data Source
AI summary
An amplifier includes a sigma-delta modulating circuit, a power stage circuit, two feedback components, an error suppressing circuit, and a selecting circuit. The sigma-delta modulating circuit generates two input voltages according to two input signals or one single-ended signal. The power stage circuit provides two output voltages according to the two input voltages or an error adjusting voltage. The two feedback components are respectively coupled to two output terminals of the power stage circuit and two input terminals of the sigma-delta modulating circuits. The error suppressing circuit is used for providing the error adjusting voltage according to the two input voltages. The selecting circuit selects outputs depending on whether the two input voltages corresponding to different logic levels or an identical logic level for adjusting the power stage circuit to suppress a mismatch error between the two feedback components.