ADC Range Extension via Analog Subtraction for SIC Interference
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Solution Overview
Problem
Modern transceivers face performance degradation due to crosstalk and interference in duplex mode, especially when multiple radio access techniques communicate simultaneously across different frequency bands, where even high-quality RF filters fail to adequately mitigate interference, and carrier aggregation mode results in increased power consumption.
Innovation Solution
The implementation of ADC range extension systems that subtract the reference signal from the composite signal in the analog domain, reducing the dynamic range required for the ADC and allowing it to convert only the estimated interference signal, thereby improving the resolution of out-of-band frequencies and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-quality RF filters are used to mitigate transmit interference in the receive band, then interference mitigation is improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent replaces the mechanical RF filtering approach with a digital signal processing approach. Specifically, the system uses an ADC to convert the composite signal to digital domain, then applies self-interference cancellation algorithms to subtract the estimated self-interference from the received signal. This substitution of digital processing for analog filtering reduces device complexity and cost while maintaining or improving interference mitigation performance.
Solution Approach 2:
The patent changes the operating parameters of the ADC by dynamically adjusting its resolution based on the signal conditions. When self-interference cancellation is active, the system can use a lower-resolution ADC since the dynamic range requirements are reduced after digital interference removal. This parameter adjustment reduces power consumption and device complexity while maintaining effective interference mitigation.
2Object-affected harmful factors
If higher transmitter linearity is used to mitigate receiver desense in carrier aggregation mode, then interference mitigation is improved, but power consumption increases
Solution Approach 1:
The patent replaces the approach of improving transmitter linearity (which requires more power) with digital self-interference cancellation. The system captures the composite signal including ACLR interference, converts it to digital, and uses signal processing to remove the interference. This digital approach achieves the same interference mitigation goal with lower power consumption compared to hardware-based linearity improvement.
Solution Approach 2:
The patent introduces the ADC and digital signal processing chain as an intermediary between the transmitter and receiver. This intermediary allows the system to measure and cancel self-interference digitally, providing a pathway to mitigate receiver desense without requiring the transmitter to operate at higher linearity levels, thus reducing power consumption.
3Measurement precision
If an ADC with high dynamic range is used to convert the composite signal for self-interference cancellation, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent applies partial action by using a lower-resolution ADC than would traditionally be required for full composite signal conversion. The system accepts that the ADC will quantize the composite signal, but then uses digital signal processing to recover the interference components. This approach achieves sufficient measurement precision for self-interference cancellation without the complexity and power consumption of a high-resolution ADC.
Solution Approach 2:
The patent performs preliminary digital signal processing operations including capturing the composite signal, converting it to digital domain, and estimating the self-interference component before final reception processing. This preliminary action allows the system to prepare the signal in a way that reduces subsequent processing requirements and enables the use of lower-resolution conversion.
4Measurement precision
If an ADC with high dynamic range is used to convert the composite signal for self-interference cancellation, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent uses partial action by deploying an ADC with lower resolution than traditionally required for full composite signal conversion. The system captures the composite signal with this lower-resolution ADC and then uses digital signal processing to extract and cancel the self-interference. This approach achieves the necessary measurement precision for effective self-interference cancellation while significantly reducing the power consumption associated with high-resolution ADC operation.
Data Source
AI summary
Systems, methods, and circuitries are provided for extending the range of an analog-to-digital converter (ADC) associated with interference cancellation. In one example a transceiver includes front end circuitry configured to transmit a radio frequency (RF) transmit signal that includes an intended signal and an interference signal. The transceiver includes self-interference cancellation (SIC) circuitry configured to control the front end circuitry based at least on a digital baseband reference transmit signal that comprises a digital representation of the intended signal. ADC range extension circuitry is provided to: receive the RF transmit signal from the front end circuitry; receive the digital baseband reference transmit signal from the SIC circuitry; approximate the interference signal by generating an analog estimated interference signal that corresponds to a difference between the RF transmit signal and the digital baseband reference transmit signal; and provide the analog estimated interference signal to the ADC.