Reconfigurable RF Front-End Attenuator for Blocker Signal Linearization
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Solution Overview
Problem
Collocated wireless RF transceivers, particularly low-power systems, face communication conflicts and performance degradation due to interference from high-power transceivers operating at similar frequency levels, leading to signal distortion and desensitization.
Innovation Solution
A frequency selective attenuator with a tunable notch filter and programmable capacitors is implemented in the victim wireless transceiver, which includes a receiver circuit coupled with an inductor and capacitors to attenuate blocker signals, optimizing distortion performance and reducing voltage swings by decoupling components based on frequency differences and operational modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a low-power wireless transceiver operates near a high-power transceiver at similar frequencies, then the low-power transceiver can achieve energy efficiency, but its reception performance deteriorates due to signal distortion and interference
Solution Approach 1:
The frequency selective attenuator divides the frequency spectrum into different segments, allowing the low-power transceiver to selectively attenuate specific high-power blocker frequencies while passing through other frequencies. This segmentation enables the receiver to filter out interfering signals at the front end, improving reception performance without increasing overall power consumption.
Solution Approach 2:
The frequency selective attenuator is placed at the front end of the receiver, performing preliminary attenuation of blocker signals before they enter the main reception chain. By preemptively reducing the strength of high-power interfering signals, the system prevents signal distortion and compression from occurring downstream, thereby maintaining reliable reception without requiring additional power for later correction.
2Object-affected harmful factors
If a frequency selective attenuator is added to the receiver front end, then blocker signal attenuation is improved, but device complexity increases
Solution Approach 1:
The frequency selective attenuator is designed to perform multiple functions: it provides frequency-selective attenuation of blocker signals, maintains impedance matching across the frequency band, and preserves desired signal integrity. By combining these functions into a single circuit module, the design achieves effective blocker attenuation without proportionally increasing overall device complexity.
Solution Approach 2:
The attenuator utilizes variable capacitance elements that can be dynamically adjusted to change the attenuation characteristics at different frequencies. By modifying electrical parameters (capacitance values) rather than adding physical components, the system adapts to different blocker frequencies and signal conditions, achieving high attenuation performance with minimal circuit complexity.
3Measurement precision
If capacitance values are optimized for frequency selectivity, then attenuation performance at blocker frequencies is improved, but voltage swing across the attenuator increases causing distortion
Solution Approach 1:
The attenuator employs different capacitor quality factors (Q-values) in different parts of the circuit. High-Q capacitors are used for frequency-selective elements to achieve precise attenuation at blocker frequencies, while low-Q capacitors are used in paths where voltage swing occurs to dampen oscillations and reduce distortion. This localized optimization of component quality allows the system to maintain both frequency selectivity and low distortion simultaneously.
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 solution enables low-power wireless transceivers to coexist with high-power transceivers by effectively attenuating blocker signals, improving reception quality and minimizing distortion, thereby enhancing RF coexistence and communication reliability.
Implementation Method 1
a frequency selective attenuator including an inductor and a first capacitor coupled in series between the radio frequency receiver node and a reference node, and a second capacitor coupled in parallel with the first capacitor
Implementation Method 2
a frequency selective attenuator including an inductor and a first capacitor coupled in series between the radio frequency receiver node and a reference node
Implementation Method 3
the first capacitor has a first capacitance based on a blocker frequency
Implementation Method 4
the second capacitor has a second capacitance that linearizes the frequency selective attenuator. The second capacitance of the second capacitor may be greater than the first capacitance of the first capacitor. The second capacitance of the second capacitor may be selected to reduce a voltage swing across the frequency selective attenuator
Data Source
AI summary
A wireless device including a receiver circuit coupled to a radio frequency receiver node, a frequency selective attenuator including an inductor and a first capacitor coupled in series to the radio frequency receiver node, and a second capacitor coupled in parallel with the first capacitor. The first capacitor has a first capacitance based on a blocker frequency and the second capacitor has a second capacitance that linearizes the frequency selective attenuator. A method of linearizing a frequency selective attenuator including detecting presence of a blocker signal, activating and programming a capacitor of the frequency selective attenuator to reduce a strength of the blocker signal, determining a frequency difference between the blocker signal and a receive frequency, and coupling a second capacitor to the frequency selective attenuator to linearize the frequency selective attenuator when the frequency difference is no more than an attenuation threshold.