Interference-Canceling ADC Architecture for Extended Dynamic Range
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Solution Overview
Problem
Existing analog-to-digital conversion systems are limited by their dynamic range, which is often constrained by the number of bits (ENoB) of the analog to digital converter (ADC), leading to challenges in handling high levels of in-band interference and requiring additional methods to extend the system's ability to process both strong interfering and weak desired signals effectively.
Innovation Solution
The system employs multiple ADCs, a DAC, a programmable delay block, a gain block, and digital signal processing to reconstruct the received signal by partially cancelling interfering signals through time-delayed subtraction and inverse distortion modeling, allowing for interference cancellation across the Nyquist bandwidth without relying on prediction or known waveforms, and handles changing interference conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ADC is used for signal conversion, then the system structure is simple, but the dynamic range is limited by the ENoB of the ADC
Solution Approach 1:
The system segments the signal conversion process into two parallel paths: a first ADC path for capturing the full bandwidth signal and a second ADC path for capturing the residual signal after interference cancellation. This segmentation allows each ADC to operate within its optimal dynamic range while collectively achieving an extended overall dynamic range that exceeds what a single ADC could provide.
Solution Approach 2:
The second ADC is nested within the signal processing chain after the first ADC's output is used to generate a cancellation signal. The residual signal from the first path is fed into the second ADC, creating a nested structure where the second conversion operates on the remaining signal components, effectively extending the total dynamic range through hierarchical signal processing.
2Measurement precision
If predictor circuits are used to estimate and cancel interfering signals, then the dynamic range can be extended, but the system requires known or predicted waveforms
Solution Approach 1:
The system uses the output from the first ADC itself to generate the cancellation signal through digital signal processing, rather than relying on external predictors or known waveform databases. The first ADC's digitized signal is processed to create the interference cancellation signal, which is then subtracted from the input. This self-service approach allows the system to adapt to changing interference conditions without requiring external prediction mechanisms.
3Object-affected harmful factors
If known transmitted waveforms are subtracted from the receive path, then interference cancellation can be achieved, but the system cannot handle changing signal interference conditions
Solution Approach 1:
The system dynamically adapts to changing interference conditions by using the real-time output from the first ADC to generate the cancellation signal. Unlike static systems that subtract predetermined known waveforms, this system continuously updates the cancellation signal based on the actual received signal characteristics, making it dynamic and adaptable to varying interference conditions while maintaining effective interference cancellation.
4Measurement precision
If higher dynamic range ADCs are used to digitize both strong interfering and weak desired signals, then the dynamic range is extended, but the cost and complexity increase
Solution Approach 1:
Instead of using a single high-dynamic-range ADC, the system segments the conversion function across two standard ADCs operating in parallel paths. The first ADC handles the full-scale signal including strong interferers, and the second ADC handles the residual signal containing weak desired components. This segmentation allows the use of moderate-range ADCs to achieve the equivalent performance of a single high-dynamic-range ADC, reducing cost and complexity.
Data Source
AI summary
Methods and apparatus for interference cancelling data conversion. In one embodiment, an input includes an interfering signal and a signal of interest. In one embodiment, a system extends the received signal dynamic range of an analog-to-digital conversion system by partially cancelling an interfering signal with multiple analog-to-digital converters, a digital-to-analog converter, a programmable delay block, a gain block, and a difference amplifier, inverse non-linear blocks, and digital signal processing to reconstruct the received signal in the digital domain.