Receiver Sample Interpolation for Low-Power Timing Accuracy
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Solution Overview
Problem
Bluetooth receivers face challenges in achieving accurate sample extraction with low power consumption and reduced complexity, particularly when operating at lower sampling frequencies, which can compromise the accuracy and increase the cost and complexity of the digital part of the receiver chain.
Innovation Solution
The implementation of an interpolating filter that generates additional digitized samples at a lower sampling rate, allowing for higher sample granularity without increasing the sample rate, and the use of an SRRC filter to process samples at a whole multiple of the baseband signal rate, eliminating ISI and reducing the need for separate oscillators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sampling frequency is reduced to lower cost and complexity, then device complexity and power consumption are reduced, but sample extraction accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing interpolation coefficients in a lookup table before the actual sampling process. This allows the system to generate additional sample points through table lookup and combination operations rather than requiring high-frequency physical sampling, thereby maintaining accuracy while operating at lower sampling rates.
Solution Approach 2:
The patent introduces an intermediary mechanism - the interpolation filter with lookup table - that mediates between the low sampling rate and the required high accuracy. The lookup table acts as an intermediary data structure that stores pre-computed values, allowing the system to achieve high-resolution sample extraction without high-frequency sampling hardware.
2Measurement precision
If sampling frequency is increased to improve sample extraction accuracy, then sample extraction accuracy is improved, but power consumption and device complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing interpolation coefficients in a lookup table before the actual sampling process. This allows the system to generate additional sample points through table lookup and combination operations rather than requiring high-frequency physical sampling, thereby maintaining accuracy while operating at lower sampling rates.
Solution Approach 2:
The patent uses copying by creating virtual sample points through interpolation rather than physically capturing them at high frequency. The lookup table stores copied and transformed versions of the original samples, allowing the system to access high-resolution data without the power consumption of high-speed ADC operations.
3Measurement precision
If additional oscillator is added to generate integer multiple frequency, then sample extraction accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the frequency multiplication function from the hardware domain and moves it to the digital signal processing domain. Instead of using additional physical oscillators to generate higher frequency samples, the system extracts the necessary information through digital interpolation operations on the existing lower-frequency samples.
Solution Approach 2:
The patent replaces the mechanical/electrical oscillator system with a digital signal processing system. The lookup table and interpolation filter substitute for additional oscillators, achieving the same functional result (high-resolution sampling) through mathematical operations rather than physical frequency generation.
4Measurement precision
If high sampling frequency is used to maintain accuracy, then sample extraction accuracy is maintained, but cost and complexity of digital part increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing interpolation coefficients in a lookup table before the actual sampling process. This allows the system to generate additional sample points through table lookup and combination operations rather than requiring high-frequency physical sampling, thereby maintaining accuracy while operating at lower sampling rates.
Solution Approach 2:
The patent uses copying by creating virtual sample points through interpolation rather than physically capturing them at high frequency. The lookup table stores copied and transformed versions of the original samples, allowing the system to access high-resolution data without the power consumption of high-speed ADC operations.
Data Source
AI summary
A receive path in a receiver including circuitry for deriving a first stream of first digitized samples from a received analog signal at a first sampling rate, and at least one interpolating filter in parallel with the first stream of first digitized samples for generating at least a second stream of digitized samples at the first sampling rate but offset with respect to the first stream by a fraction of a sample time period.