High-Pass Filter Pole Switching for Fast DC Offset Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high pass filters take a long time to reach a steady state for DC offset removal, failing to converge within a suitable time period in some applications, necessitating a faster response.
Innovation Solution
A method and apparatus using a high pass filter with dynamically adjustable pole coefficients, selecting different pole frequencies for different phases of an input signal to quickly estimate and remove DC offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high pass filter is used to remove DC offset, then DC offset removal is achieved, but the filter takes a long time to reach steady state
Solution Approach 1:
The patent applies dynamics by making the pole coefficient of the high pass filter adjustable rather than fixed. The system dynamically changes the pole coefficient from a first value during an initial period to a second value after the initial period, allowing the filter to adapt its response characteristics over time to achieve both fast settling and effective DC offset removal.
Solution Approach 2:
The patent changes the parameter (pole coefficient) of the high pass filter over time. By transitioning the pole coefficient from a first value to a second value after an initial period, the system modifies the filter's frequency response characteristics to balance between rapid settling and thorough DC offset elimination.
2Device complexity
If a high pass filter with fixed pole coefficient is used, then the filter structure is simple, but the DC offset cannot converge within a suitable time period
Solution Approach 1:
The system transitions from a static filter configuration to a dynamic one by introducing adjustable pole coefficients. This allows the filter to optimize its convergence speed without requiring a completely complex multi-stage architecture, maintaining relative simplicity while improving performance.
Solution Approach 2:
The system performs preliminary DC offset removal during an initial period using a first pole coefficient, then transitions to a second pole coefficient for continued refinement. This staged approach enables faster overall convergence compared to a single fixed coefficient design.
Data Source
AI summary
There are provided methods and apparatuses for removing a DC offset from an input signal, comprising: receiving the input signal having a first phase and a second phase; applying a high pass filter to the input signal, wherein a transfer function of the high pass filter has a pole coefficient that determines a pole frequency of the high pass filter, comprising: selecting a first pole coefficient of the high pass filter for the first phase, estimating DC offset of the input signal during the first phase, and selecting a second pole coefficient of the high pass filter for the second phase, wherein the first pole coefficient and the second pole coefficient are selected such that the first pole frequency is higher than the second pole frequency; and removing the DC offset from the input signal.