Reconfigurable Analog Filter Offset Compensation Without Auto-Zero Delay
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Solution Overview
Problem
Reconfigurable analog filters face challenges with direct current (DC) offset variations when changing configurations, leading to time overhead and transient errors due to the need for auto-zero procedures, which introduce noise and signal couplings.
Innovation Solution
A method involving pre-calibration to determine DC offset correction values for different filter configurations, storing these values in memory, and converting them to analog signals using DACs to apply compensation during operation, eliminating the need for auto-zero procedures and reducing transient errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated auto-zero procedure is performed every time the filter is reconfigured, then DC offset corrections are provided for various filter configurations, but time overhead is added to channel usage
Solution Approach 1:
The patent pre-calculates and stores DC offset correction values for multiple filter configurations in a lookup table during manufacturing or initialization. When the filter is reconfigured, the corresponding pre-computed correction value is directly retrieved from memory without performing real-time auto-zero procedures, thereby eliminating the time overhead while maintaining correction accuracy
Solution Approach 2:
The patent prepares compensation measures in advance by storing correction values for various configurations before operation. This beforehand cushioning ensures that when reconfiguration occurs, the system already has the necessary correction data ready, avoiding the need for time-consuming post-reconfiguration auto-zero procedures
2Reliability
If a dedicated auto-zero procedure is performed every time the filter is reconfigured, then DC offset corrections are provided, but transient errors occur due to noise and signal couplings
Solution Approach 1:
The patent performs DC offset characterization and correction value computation in advance during manufacturing or initialization, storing these pre-computed values in a lookup table. During operation, when the filter is reconfigured, the system simply retrieves the corresponding pre-stored correction value without executing auto-zero procedures, thereby completely avoiding transient errors caused by noise and signal couplings that occur during real-time auto-zero operations
3Adaptability or versatility
If the filter bandwidth is scaled in proportion to the data rate, then the filter adapts to different data rates, but DC offset varies with bandwidth changes
Solution Approach 1:
The patent pre-characterizes the DC offset behavior for different filter bandwidths and configurations during manufacturing, storing the corresponding correction values in a lookup table indexed by bandwidth or configuration parameters. When the filter bandwidth is scaled to adapt to different data rates, the system retrieves the appropriate pre-computed correction value based on the new bandwidth setting, maintaining DC offset stability across bandwidth variations without requiring real-time re-characterization
Solution Approach 2:
The patent utilizes the relationship between bandwidth and DC offset by pre-computing correction values for different bandwidth settings. When bandwidth parameters change during operation, the system changes the selected correction value parameter from the lookup table accordingly, allowing the filter to adapt to different data rates while maintaining stable DC offset compensation through parameter substitution rather than real-time computation
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 reduces the time overhead associated with reconfiguring filters, improves format efficiency, and minimizes transient errors, enhancing overall system performance by applying precise DC offset compensation without delaying operations.
Implementation Method 1
converting, with one or more digital to analog converters (DACs), the one or more DC offset correction codes in the first set to one or more first analog DC offset correction signals
Data Source
AI summary
During operation of an analog filter having one or more filter stages is configured to operate in a first configuration. Configuring the analog filter to operate in the first filter configuration includes configuring one or both of i) a filter response of the analog filter and ii) a filter bandwidth of the analog filter. A first set of one or more direct current (DC) offset correction codes corresponding to the first filter configuration are retrieved from a memory. The one or more DC offset correction codes in the first set are converted to one or more first analog DC offset correction signals. While operating the analog filter configured in the first configuration, the one or more first analog DC offset correction signals are applied to the one or more filter stages of the analog filter.