HF Power Measurement Chopper Circuit for Wide Dynamic Range
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Solution Overview
Problem
Existing high-frequency signal power measuring devices face complexity and accuracy issues due to the use of parallel measurement branches, leading to synchronization challenges and poor signal levels at the dynamic range extremes.
Innovation Solution
A single-path measuring device is implemented with a chopper placed before the DC amplifier to reduce 1/f noise and thermal drift, using a dither signal synchronized with the chopper to optimize analog/digital conversion and minimize discretization errors by maintaining a constant dither signal during measurement series.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parallel measurement branches are used to cover maximum dynamic range, then measurement precision is improved, but device complexity increases extremely
Solution Approach 1:
The patent segments the measurement process into multiple dynamic ranges using a single measurement branch with variable gain settings. Instead of using parallel branches for different dynamic ranges, the system sequentially adjusts the gain of a single branch to handle different signal levels, thereby reducing complexity while maintaining measurement precision across the full dynamic range.
Solution Approach 2:
The patent employs dynamic gain adjustment in the single measurement branch to adapt to different signal levels. The gain setting is changed based on the signal characteristics, allowing the system to maintain optimal measurement precision across the entire dynamic range without requiring multiple parallel branches. This dynamic adaptation simplifies the overall device architecture.
2Device complexity
If single-path realization is used to reduce complexity, then device complexity is reduced, but measurement precision deteriorates due to poor signal level at lower end of dynamic range
Solution Approach 1:
The patent changes the gain parameter of the single measurement branch dynamically to optimize signal levels across the entire dynamic range. By adjusting the gain setting based on the input signal characteristics, the system maintains adequate signal levels at the lower end of the dynamic range, thereby preserving measurement precision without requiring multiple parallel branches.
Solution Approach 2:
The patent implements feedback mechanisms to monitor signal levels and automatically adjust the gain setting of the single measurement branch. This feedback control ensures that the signal level remains within the optimal range for accurate measurement, preventing distortion and maintaining precision across the full dynamic range while using a single path architecture.
3Measurement precision
If chopper is added to reduce 1/f noise and thermal drift, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces a chopper as an intermediary component between the sensor and the measurement circuitry. The chopper modulates the signal to shift it to a higher frequency range, thereby separating it from low-frequency noise and thermal drift artifacts. This intermediary approach effectively reduces 1/f noise and thermal drift without requiring complex filtering or multiple measurement branches, maintaining relative simplicity.
Solution Approach 2:
The patent employs periodic chopping of the signal to reduce 1/f noise and thermal drift. By periodically modulating the signal and using synchronous detection, the system converts low-frequency noise and drift into high-frequency components that can be easily filtered out. This periodic action approach effectively reduces noise without requiring complex continuous filtering mechanisms.
4Adaptability or versatility
If dither signal is alternated asynchronously with chopper signal, then adaptability is improved, but measurement precision deteriorates due to additional waiting times for settling
Solution Approach 1:
The patent synchronizes the dither signal alternation with the chopper signal periodicity. By alternating the dither signal in sync with the chopper phases, the system eliminates additional settling wait times that would occur with asynchronous alternation. The dither signal is switched at the same moments as the chopper signal, ensuring that the measurement circuitry is always in a stable state ready for accurate measurement, thereby maintaining precision while preserving adaptability.
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 enhances measurement accuracy and reduces noise, allowing for precise power measurement across a wide dynamic range without the need for complex synchronization and additional waiting times, improving signal quality and reducing errors.
Implementation Method 1
a chopper in front of the DC amplifier, which periodically chops the analog detector signal with a chopper signal
Implementation Method 2
the signal inversion caused by chopping can subsequently be removed from the digital signal by a synchronous demodulator
Implementation Method 3
a dither signal is supplied to the chopper signal in a synchronous manner before the analog/digital conversion
Data Source
AI summary
A measuring device for measuring the power of a high-frequency signal including a detector for detecting the high-frequency signal and for generating an analog detector signal, an analog/digital converter for generating a digital signal and an evaluation device for evaluating the digital signal. A dither supply device for the supply of a dither signal and a chopper, which periodically chops the analog detector signal with a chopper signal, are disposed between the detector and the analog/digital converter. In this context, the dither signal is supplied synchronously to the chopper signal.