Active Tone Canceller for Spurious Signal Suppression
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Solution Overview
Problem
Existing methods to suppress spurious signals in semiconductor devices and communication networks are inadequate, as they often attenuate signal portions and fail to effectively eliminate noise, leading to interference with communication signals like Bluetooth and WiFi.
Innovation Solution
An active canceller system that estimates the magnitude and phase of spurious signals using a magnitude estimator and phase estimator, generating a tone signal to subtract from the channel signal in the time domain, thereby suppressing spurious signals without transforming the channel signals into the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional notch filters are used to suppress spurious signals, then spurious signals are attenuated, but signal portions are also attenuated and noise is not effectively eliminated
Solution Approach 1:
The patent extracts only the spurious signal components from the channel signal by estimating their magnitude and phase, then subtracts only these extracted components. This selective extraction approach allows suppression of spurious signals while preserving useful signal portions, overcoming the limitation of traditional notch filters that attenuate both spurious signals and useful signal portions.
Solution Approach 2:
The patent converts the harmful spurious signals into beneficial information by estimating their magnitude and phase characteristics. These estimated characteristics are then used to generate cancellation tones that actively subtract the spurious signals. This transformation turns the harmful spurious signals into useful data for their own cancellation, effectively eliminating noise while maintaining signal quality.
2Object-affected harmful factors
If spurious signals are suppressed in the frequency domain, then noise reduction is achieved, but channel signals must be transformed which increases processing complexity
Solution Approach 1:
Instead of transforming channel signals into the frequency domain for noise suppression, the patent inverts the conventional approach by performing all processing in the time domain. The magnitude and phase estimators operate on time-domain signals, and the cancellation is achieved through time-domain subtraction. This inversion eliminates the need for complex frequency-domain transformations while achieving effective noise reduction.
Solution Approach 2:
The patent substitutes the mechanical frequency-domain transformation process with a time-domain signal processing approach. By replacing the Fourier transform and frequency-domain filtering operations with time-domain magnitude and phase estimation followed by time-domain subtraction, the system achieves noise suppression with reduced processing complexity and lower computational overhead.
3Object-affected harmful factors
If magnitude and phase estimation is performed continuously, then spurious signals are effectively cancelled, but processing time is increased during signal transmission
Solution Approach 1:
The patent performs magnitude and phase estimation during periods when no channel signals are transmitted, such as training sequences or silent intervals. This preliminary action allows the system to characterize spurious signals before actual communication begins, storing the estimated magnitude and phase information for use during signal transmission. This approach eliminates processing time during communication while still achieving effective spurious signal cancellation.
Data Source
AI summary
An active canceller includes a magnitude estimator, a phase estimator, a tone generator, and a suppressor. The magnitude estimator estimates the magnitude of spurious signals on a channel. The phase estimator estimates the phase of the spurious signals on the channel. The tone generator generates a tone signal based on the estimated magnitude and phase. The suppressor subtracts the tone signal from a channel signal to suppress the spurious signals. The magnitude and phase estimators and the suppressor may operate in the time domain.