Digital Interpolation and Decimation with Dynamic Low-Power Path Switching
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Solution Overview
Problem
Digital interpolators and decimators in audio codecs face challenges in balancing performance and power consumption, as higher performance requirements for passband ripple and stopband attenuation often lead to increased power consumption, which is particularly problematic in battery-powered devices.
Innovation Solution
A multi-path approach is implemented, where a digital circuit includes two paths with different power consumption and performance levels, with a selection circuit determining the spectral content or signal level to switch between these paths, using the lower power path for lesser spectral content or signal levels and the higher power path for richer content or higher levels, and employing cross-fading to minimize signal artifacts during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher performance filtering is used to improve passband ripple and stopband attenuation, then filter performance is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic path selection where the interpolator switches between a first path with lower power consumption and a second path with higher power consumption based on input signal characteristics. The selection circuit dynamically determines which path to use, making the system adaptable to varying signal conditions rather than operating at fixed performance levels.
Solution Approach 2:
The patent changes operational parameters by switching between different processing paths with distinct power consumption characteristics. The selection circuit monitors input signal parameters (such as signal level or spectral content) and adjusts the operating path accordingly, effectively changing the power consumption parameter based on actual signal requirements.
2Measurement precision
If a single high-performance path is used for all input signals, then filter performance is maintained, but power consumption increases for all conditions
Solution Approach 1:
The patent applies partial action by using only the necessary filtering performance required for each specific input signal. Instead of always applying full high-performance filtering, the system selectively applies high-performance filtering only when the input signal characteristics warrant it, while using lower-power paths for signals that don't require such stringent filtering.
Solution Approach 2:
The dynamic path selection mechanism allows the system to adapt its performance level to match the actual requirements of each input signal. The selection circuit continuously evaluates signal characteristics and adjusts the processing path accordingly, preventing unnecessary power consumption while maintaining adequate performance.
3Use of energy by moving object
If multiple paths with different power consumption levels are implemented, then power efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the filtering function into multiple distinct paths, each optimized for different power consumption requirements. The first path is designed for lower power consumption while the second path provides higher performance when needed. This segmentation allows the system to distribute the filtering workload across specialized sub-systems rather than using a single general-purpose high-performance path.
Solution Approach 2:
The selection circuit acts as an intermediary that manages the complexity of multiple paths. It monitors input signal characteristics and automatically routes signals through the appropriate path, shielding the user from the underlying complexity while enabling power-efficient operation. The intermediary handles the decision-making logic, simplifying the overall system control.
Data Source
AI summary
An apparatus performs interpolation/decimation in a digital circuit that receives an input signal and includes upsampling/downsampling and filtering stages. First and second paths include distinct first and second portions of the upsampling/downsampling and filtering stages. The first path consumes less quiescent state power. A selection circuit uses the first or second path and turns off the unused first or second path based on input signal spectral content or level. A mode includes applying a front-end digital/analog gain and a corresponding back-end analog/digital attenuation in conjunction with the first path being used and the second path being turned off. A cross-fader uses the first and second paths in a weighted mix manner while making a transition between using the first and second paths. The second path has higher filtering performance (e.g., superior stopband attenuation, passband ripple, transition band, e.g., via higher order or greater bit-width filtering).