Programmable RF Front End for Wideband ADC Interference Mitigation
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Solution Overview
Problem
Wideband ADCs face challenges with reduced dynamic range due to smaller input voltage swings, increased signal observation, and greater impact from interfering signals, with existing solutions limited in handling multiple interferers.
Innovation Solution
A programmable RF front end is integrated into an RFSoC-based receiver system, allowing flexible allocation of ADC resources by programming each signal channel with tunable bandpass filters and mixer frequencies to mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If wideband ADCs are used to capture wide signal bandwidth, then bandwidth coverage is improved, but dynamic range is reduced due to smaller input voltage swings
Solution Approach 1:
The receiver system is divided into multiple parallel signal channels, each with its own ADC. This segmentation allows the system to distribute the wideband coverage across multiple narrower channels, each maintaining adequate dynamic range while collectively providing comprehensive bandwidth coverage.
Solution Approach 2:
The system dynamically allocates ADC resources to different frequency bands based on interference conditions. The programmable RF front end can reconfigure which ADCs monitor which frequency ranges, allowing optimal use of available dynamic range while maintaining wideband coverage capability.
2Speed
If the bandwidth of ADC is increased to observe more signals, then frequency coverage is improved, but dynamic range is further stressed and reduced
Solution Approach 1:
Multiple ADCs are used in parallel, with each ADC responsible for a specific frequency band or channel. This divides the total frequency coverage requirement into smaller segments that each ADC can handle without excessive dynamic range demands.
Solution Approach 2:
The system uses a bank of ADCs that can be programmatically assigned to different frequency bands. Each ADC serves multiple potential functions across different bands, and the system universally applies the same ADC resource pool to cover the entire frequency spectrum through software control.
3Object-affected harmful factors
If existing notch filter solutions are used to remove interferers, then interference mitigation is improved for limited cases, but the number of interferers that can be handled is limited
Solution Approach 1:
The system assigns different ADCs to monitor different frequency channels, with each ADC potentially having its own notch filter. This segmentation allows multiple interferers to be handled simultaneously by distributing the interference mitigation task across multiple ADC channels.
Solution Approach 2:
The system dynamically configures which ADCs monitor which frequency bands and applies notch filters adaptively based on detected interferers. This dynamic reconfiguration allows the system to handle a variable number of interferers across different frequency locations without being limited by a fixed filter structure.
Data Source
AI summary
A receiver includes an antenna block configured to transduce impinging electromagnetic signals into electrical signals; a signal conditioning block configured to condition electrical signals received from the antenna block; and a down-converter block configured to down-convert conditioned electrical signals received from the signal conditioning block. The down-converter block comprises a plurality of signal channels. The receiver further includes a plurality of analog-to-digital converters (ADCs) respectively connected to the signal channels of the down-converter block; and a field-programmable gate array (FPGA). The FPGA is configured to program the down-converter block by selecting a set of mixer frequencies and a set of bandwidths designed to remove interference signals in each signal channel. The selections are calculated to mitigate reductions in dynamic range in the ADCs due to interference. The FPGA is further configured to process digital signals received from the ADCs after the down-converter block has removed the interference signals.