Differential Impedance Balance Circuits for On-Situ Mismatch Correction
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Solution Overview
Problem
Differential signal processing systems face performance degradation due to impedance mismatches between positive and negative branches, leading to incomplete cancellation of noise and nonlinearity, which are difficult to address without costly engineering techniques and time-consuming development.
Innovation Solution
Implementing a digitally controlled impedance array that senses and compensates for impedance mismatches by injecting common mode stimuli and adjusting digitally controllable impedances to rebalance the signal path on-situ, using a Wheatstone bridge structure and algorithms to determine the necessary impedance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digitally controlled impedance is used to compensate for impedance mismatches, then signal processing linearity is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by using digitally controlled impedance elements that can dynamically adjust their impedance values to compensate for mismatches. The system measures the actual impedance of differential signal paths and programmatically adjusts the digitally controlled impedance to achieve balance, thereby improving signal processing linearity without requiring complex manual calibration
Solution Approach 2:
The patent implements self-service through an automated calibration system that performs self-diagnosis and self-correction. The system automatically measures impedance mismatches using test circuits, calculates the required compensation, and adjusts the digitally controlled impedance elements without external intervention, reducing the need for costly engineering techniques and time-consuming development
2Reliability
If common mode calibration circuitry is used to calibrate out impedance differences, then differential signal processing performance is improved, but circuit complexity increases
Solution Approach 1:
The patent applies preliminary action by performing impedance calibration before normal signal processing operations. The system uses test circuits to measure impedance mismatches and adjusts the digitally controlled impedance elements in advance, ensuring optimal differential signal processing performance before actual signal transmission begins
Solution Approach 2:
The patent uses an intermediary approach by introducing digitally controlled impedance elements as adjustable components between the differential signal sources and loads. These intermediary elements provide fine-tunable impedance adjustment to compensate for mismatches, improving signal processing reliability while maintaining manageable circuit complexity through integrated control
3Ease of manufacture
If impedance mismatch compensation is performed on-situ, then manufacturing cost is reduced, but measurement precision requirements increase
Solution Approach 1:
The patent replaces mechanical or manual impedance adjustment mechanisms with electronically controlled systems. Instead of physical trimming or manual calibration, the system uses digitally controlled impedance elements that can be programmatically adjusted based on electronic measurements, reducing manufacturing costs while achieving precise compensation through software-controlled calibration algorithms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces impedance mismatches, improving signal processing linearity and performance by compensating for mismatches on-situ, prior to normal operation, without the need for extensive engineering efforts, thereby enhancing the cancellation of noise and nonlinearity.
Implementation Method 1
using a Wheatstone bridge structure and algorithms to determine the necessary impedance values
Data Source
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AI summary
Circuits are used to sense and compensate or mitigate the imbalance errors, hence restoring the intended benefits of differential processing. In particular, the impedance mismatch between the positive and negative branches of a balanced system is sensed by digitizing an error voltage developed by injecting suitable common mode stimuli. The mismatch is then trimmed out by introducing and properly setting up a digitally controlled impedance that counters the original impedance mismatch and hence rebalances the signal path on-situ and prior to exercising the signal processing chain.