Mixed-Signal Feedback Filter for Stable Interference Rejection
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Solution Overview
Problem
Existing filter systems for wireless communication signals face challenges in efficiently removing unwanted signal power, as analog filters are expensive and bulky, while digital filters require high-resolution and high-dynamic-range ADCs that are costly and power-hungry, and adaptive filter algorithms suffer from time delays and instability.
Innovation Solution
A mixed-signal filter that combines analog and digital components, using an analog signal path, an ADC, a programmable digital feedback filter, and a DAC to generate a predetermined transfer function, allowing for effective filtering of unwanted signal power without the drawbacks of adaptive algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog filter systems are used to filter specific frequencies in the frequency spectrum, then filtering performance is improved, but cost and device size increase significantly
Solution Approach 1:
The filter system is segmented into two distinct domains: an analog domain for signal reception and initial processing, and a digital domain for precise frequency filtering. The analog-to-digital converter acts as the segmentation boundary, allowing each domain to perform its optimal function while reducing overall system complexity.
Solution Approach 2:
The analog-to-digital converter serves as an intermediary component that bridges the analog and digital domains. It enables the transition from analog signal reception to digital signal processing, allowing the system to leverage the strengths of both domains without requiring a purely complex analog filter system.
2Device complexity
If digital filters are used to filter communication signals, then cost and algorithm complexity are reduced, but high-resolution and high-dynamic-range ADCs are required which increase cost and power consumption
Solution Approach 1:
The system applies partial digital filtering rather than requiring complete high-resolution digital processing. By using a moderate-resolution ADC combined with digital filtering, the system achieves effective frequency filtering without the excessive power consumption and cost associated with high-resolution ADCs.
3Measurement precision
If adaptive filter algorithms are used to continuously monitor and cancel interferer signals, then signal filtering capability is improved, but time delays and stability issues occur
Solution Approach 1:
The system performs preliminary frequency identification and filtering setup before interferer signals fully impact the communication signal. By pre-configuring the digital filter based on known interferer frequencies or preliminary analysis, the system avoids the time delays and stability issues associated with continuous adaptive monitoring and adjustment.
Data Source
AI summary
One embodiment of the invention includes a mixed-signal filter. The mixed-signal filter comprises an analog signal path configured to process a first analog signal and an analog-to-digital converter (ADC) configured to convert the processed first analog signal to a digital signal. The mixed-signal filter also comprises a programmable digital feedback filter configured to filter the digital signal and a digital-to-analog converter (DAC) configured to convert the filtered digital signal to a second analog signal. The mixed-signal filter further comprises a signal combiner configured to combine an analog input signal of the mixed-signal filter and the second analog signal to generate the first analog signal.