Digital Filter Chain Gain Merging for Higher SNR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing digital filter chains, particularly those including IIR filter elements, face challenges in optimizing signal-to-noise ratio (SNR) and bandwidth utilization due to quantization errors and unnecessary bitshifts introduced by adjacent gain operations.
Innovation Solution
The implementation of a common gain element in filter chains, which combines adjacent output and input gains to minimize quantization errors and reduce precision loss, along with the use of a programmable bitwidth extension value to optimize bitwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate output gain and input gain operations are used in adjacent filter stages, then flexibility in gain adjustment is improved, but quantization errors and precision loss increase
Solution Approach 1:
The patent combines separate output gain and input gain operations into a single common gain operation. Instead of applying gain1 at the output of the first filter and gain2 at the input of the second filter, the patent merges these into one common gain element that processes the intermediate signal once, eliminating redundant quantization operations and reducing precision loss while maintaining the ability to adjust overall gain.
Solution Approach 2:
The common gain element serves multiple functions simultaneously: it performs the output gain function for the first filter stage and the input gain function for the second filter stage in a single operation. This multi-functional approach eliminates the need for separate gain elements while preserving the flexibility to adjust the gain characteristics of the filter chain.
2Adaptability or versatility
If multiple separate gain elements are used in filter chains, then gain control flexibility is improved, but device complexity increases
Solution Approach 1:
The patent reduces device complexity by merging multiple separate gain elements into a single common gain element. This consolidation eliminates redundant components in the filter chain while maintaining the ability to control gain characteristics, thereby simplifying the overall device structure without sacrificing adaptability.
3Adaptability or versatility
If adjacent gain operations with opposite bitshifts are performed, then gain adjustment range is improved, but quantization errors increase
Solution Approach 1:
The patent merges adjacent gain operations with opposite bitshifts into a single common gain operation. By performing the gain adjustment in one operation rather than multiple sequential operations, the patent eliminates intermediate quantization errors that would otherwise accumulate, thereby improving signal quality while maintaining the full gain adjustment range.
Data Source
AI summary
Methods and apparatus are provided for adapting gain elements in digital filter chains. In one example, a digital filter chain includes a first digital filter and a second digital filter. The first digital filter includes a fixed point finite impulse response (FIR) filter and includes an output gain element. The second digital filter has an input coupled to an output of the first digital filter and includes an IIR filter. The output gain element applies a common output gain value that is based on a product of an input gain configured in association with the second digital filter and an FIR output gain that is based on a scaling factor K associated with the first digital filter.