Adaptive RF Receiver Tuning for Filter Frequency Drift
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Solution Overview
Problem
Conventional RF receivers face challenges due to center frequency shifts in channel selection filters caused by process variations and temperature changes, leading to signal degradation and increased design complexity, particularly in mobile communications where chip size, power consumption, and cost must be minimized.
Innovation Solution
An adaptive receiver is developed, utilizing a two-dimensional or one-dimensional look-up table to estimate the center frequency of a band pass filter based on temperature and process corner values, with a local oscillator generating sinusoidal signals to compensate for frequency shifts, allowing for accurate intermediate frequency conversion and minimizing design complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automatic tuning circuitry is used to control filter frequency response, then frequency accuracy is improved, but device complexity increases
Solution Approach 1:
The patent pre-calculates and stores frequency offset values in a lookup table during the design phase, covering various temperature and process corner conditions. During operation, the microcontroller simply retrieves the appropriate offset value from the table based on measured temperature and process parameters, eliminating the need for complex real-time tuning circuitry while maintaining frequency accuracy
Solution Approach 2:
The patent replaces automatic tuning circuitry (electrical/electronic system) with a microcontroller-based software solution that uses a lookup table. This substitution reduces hardware complexity by replacing analog tuning components with digital processing, achieving frequency compensation through computational methods rather than electrical tuning circuits
2Ease of manufacture
If conventional BPF is used, then manufacturing simplicity is maintained, but signal quality deteriorates due to center frequency shift
Solution Approach 1:
The patent implements a feedback mechanism where the microcontroller measures the actual center frequency of the BPF using test tones, compares it with the expected frequency, and retrieves a compensating offset value from the lookup table. This closed-loop feedback system maintains signal quality by continuously correcting for frequency shifts while keeping the BPF design simple
Solution Approach 2:
The patent changes the operating parameters of the system by introducing temperature and process corner as variables. The lookup table stores frequency offset values corresponding to different combinations of these parameters, allowing the system to adapt to manufacturing variations and environmental changes without modifying the physical BPF design
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The adaptive receiver effectively compensates for frequency shifts due to temperature and process variations, maintaining signal quality while reducing design complexity and costs, making it suitable for mobile communications applications.
Implementation Method 1
a local oscillator to generate sinusoidal signals at a frequency FLO equal to FRF minus FC
Data Source
AI summary
An adaptive receiver for receiving a radio frequency (RF) signal and converting the RF signal at an RF frequency FRF toward a low intermediate frequency FIF is disclosed. The adaptive receiver comprises a pair of band pass filters with a nominal center frequency Fc equal to FIF, a look-up table (LUT) configured to estimate a frequency offset Δf, representing the center frequency of the band pass filter due to an operating temperature change and/or process variation, a micro controller configured to estimate the operating center frequency of the band pass filter (=FIF+Δf with the frequency offset included) and use this new center frequency as the adaptive intermediate frequency FIF,AD, and a local oscillator generates oscillating signals at a frequency FLO equal to FRF minus FIF,AD. A temperature sensing device may also be included in this adaptive receiver.