Sampling Rate Conversion Using NCO Calibration and Interpolation
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Solution Overview
Problem
Existing communication systems face challenges in efficiently converting digital signals between different sampling rates due to the need for multiple filters and phase locked loops, leading to increased chip area and power consumption, as well as limited flexibility in handling varying sampling rates.
Innovation Solution
A device and method utilizing a numeric controlled oscillator and interpolation filter to generate calibrating coefficients, allowing for seamless conversion of digital signals between sampling rates, eliminating the need for phase locked loops and reducing the number of filters required, thereby minimizing chip area and power consumption while enhancing flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional phase locked loops and multiple filters are used for data rate conversion, then sampling rate conversion can be achieved, but chip area and power consumption increase
Solution Approach 1:
The patent extracts and removes the phase locked loop component from the data rate conversion system, replacing it with a numeric controlled oscillator that directly generates calibration coefficients. This extraction eliminates the complex feedback mechanism while retaining the essential function of sampling rate conversion, thereby reducing chip area.
Solution Approach 2:
The patent merges the functions of multiple filters into a single interpolation filter structure. By combining what would traditionally require separate filtering stages into one unified filter that processes samples at the higher rate, the patent reduces the total number of filter components needed, thus decreasing chip area while maintaining conversion capability.
2Adaptability or versatility
If traditional phase locked loops and multiple filters are used for data rate conversion, then sampling rate conversion can be achieved, but power consumption increases
Solution Approach 1:
By removing the phase locked loop from the system, the patent eliminates a major source of power consumption associated with continuous feedback operation. The numeric controlled oscillator consumes significantly less power as it operates open-loop, generating calibration coefficients directly without the energy-intensive feedback correction mechanism.
Solution Approach 2:
By merging multiple filter operations into a single interpolation filter, the patent reduces the total computational load and number of active components. This consolidation decreases the overall power consumption while maintaining the same data rate conversion functionality.
3Device complexity
If fixed filter structures are used, then implementation is simple, but flexibility in handling varying sampling rates is limited
Solution Approach 1:
The patent implements a dynamic calibration coefficient generation mechanism using a numeric controlled oscillator. Instead of using fixed filter coefficients, the system dynamically generates calibration coefficients based on the ratio between first and second sampling rates. This allows the interpolation filter to adapt to any sampling rate conversion ratio while maintaining a relatively simple fixed filter structure.
Solution Approach 2:
The patent changes the parameters (calibration coefficients) of the interpolation filter based on the specific sampling rate conversion required. By adjusting these coefficients according to the ratio L/M, the system achieves flexibility in handling various sampling rates without changing the fundamental filter structure, thus balancing simplicity and adaptability.
Data Source
AI summary
Data rate conversion devices and methods are provided. A method for converting a first digital signal having a first sampling rate into a second digital signal having a sampling rate close to a predetermined second sampling rate comprises the following operations: when the ratio of the first sampling rate to the second sampling rate is a repeating infinite decimal, calculate at least two calibrating coefficient values and output the calibrating coefficient values according to a predetermined rule; conduct overflow operation on the output calibrating coefficient; and interpolate the first digital signal using the output calibrating coefficient and the result of the overflow operation to obtain the second digital signal such that during any period of a certain length along time axis, sampling times of the second digital signal equals to sampling times of the second sampling rate.