Wireless Transmitter Circuitry for Self-Interference Cancellation
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Solution Overview
Problem
Existing wireless transmitter circuitry in electronic devices often suffer from self-interference, which degrades radio-frequency signals and limits performance due to the repetition of self-interferer replicas landing on the carrier frequency, causing error vector magnitude (EVM) degradation and spectral regrowth.
Innovation Solution
A self-interference canceller is integrated into the digital transmitter circuitry, utilizing a multiphase or polar architecture to convert signals into different formats, generate self-interference terms, apply FIR filters, and use multipliers and adders to cancel out these interference effects, optimizing performance without bulky analog components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-interference cancellation circuitry is added to the digital transmitter, then radio-frequency signal quality is improved by reducing EVM degradation and spectral regrowth, but device complexity increases due to additional conversion circuitry, self-interference term generators, FIR filters, multipliers, and adders
Solution Approach 1:
The self-interference cancellation function is segmented into distinct modular components: conversion circuitry for signal format transformation, self-interference term generators for interference component extraction, FIR filters for frequency domain processing, multipliers for coefficient application, and adders for cancellation signal synthesis. Each module performs a specific function in the signal processing chain, allowing independent optimization and maintenance while collectively achieving EVM degradation reduction and spectral regrowth suppression.
2Volume of moving object
If digital domain self-interference cancellation is used instead of analog components, then device size and cost are reduced by eliminating bulky analog components, but manufacturing precision requirements increase for the digital signal processing components
Solution Approach 1:
The patent replaces traditional analog self-interference cancellation hardware (which would require bulky RF components, filters, and mixers operating at high frequencies) with a digital signal processing implementation. The conversion circuitry transforms signals into multiphase basis vectors or polar amplitude and phase representations, enabling self-interference cancellation through digital computation rather than analog circuitry. This substitution dramatically reduces physical size while shifting precision requirements to the digital domain where they can be managed through software algorithms and high-resolution fixed-point or floating-point arithmetic.
3Measurement precision
If self-interference cancellation processing is performed at high sample rates, then signal processing accuracy is improved, but processing speed and power consumption increase
Solution Approach 1:
The self-interference canceller is designed to operate flexibly at different sample rates depending on the specific application requirements and signal characteristics. The digital signal processing components (FIR filters, multipliers, adders) can be configured to process signals at the native high sample rate for maximum accuracy, or at reduced sample rates when lower precision is acceptable. This dynamic adaptability allows the system to optimize the trade-off between cancellation accuracy and processing throughput based on real-time conditions, such as adjusting the number of FIR filter taps or the precision of coefficient calculations.
Data Source
AI summary
An electronic device may include wireless circuitry with a baseband processor, a digital transmitter, a digital-to-analog-converter (DAC), and an antenna. The baseband processor may produce baseband signals. The digital transmitter may generate self-interference-compensated signals based on the baseband signals. The DAC may generate radio-frequency signals for transmission by the antenna based on the self-interference-compensated signals and square-wave local oscillator waveforms. The digital transmitter may include a self-interference canceller that generates the self-interference-compensated signals. The self-interference-compensated signals may mitigate the creation of self-interferer repetition replicas that land on the carrier frequency of the radio-frequency signals. This may allow the radio-frequency signals to be free from error vector magnitude degradation and spectral regrowth that would otherwise be produced due to self-interference in the radio-frequency signals output by the DAC.