A method for signal modulation using pulse width modulators

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This patent describes a method for improving signal modulation using two pulse width modulators (PWMs) driven by phase-shifted reference signals. By modulating an input signal with these PWMs and destructively combining certain spectral components, the technique significantly reduces unwanted out-of-band signal content and intermodulation noise, resulting in a more efficient and spectrally pure 2- or 3-level signal. This method also defines various transmitter architectures optimized for efficient amplification and transmission of the modulated signal, applicable to both electrical and optical domains.

Use CasesContent extracted from patent full text and abstract with AI.

• Radio transmitters for wireless communication base stations (e.g., cellular networks).
• Switching power amplifiers for efficient RF signal amplification.
• Digital audio amplifiers (such as class D amplifiers) with improved performance.
• Power electronics applications such as electric motor speed control or LED brightness control with enhanced spectral properties.
• Optical communication systems using electro-optical modulators to transmit high-efficiency signals over fiber.
• Transmitter modules in wireless infrastructure requiring low power consumption and high spectral purity.

BenefitsContent extracted from patent full text and abstract with AI.

• Greatly improved coding efficiency in switched-mode transmitters (e.g., from ~12% to over 40%), meaning more of the output power is useful content and less is wasted as noise.
• Significantly reduced out-of-band noise and spectral distortions, resulting in easier filtering, less interference, and compliance with electromagnetic compatibility requirements.
• Lower power consumption and higher energy efficiency due to reduced unwanted signal components and more efficient amplification stages.
• Simplified filter requirements after amplification, potentially reducing component costs and complexity.
• Flexible architecture compatible with both electrical and optical modulation and transmission schemes.
• Adaptable to high-frequency RF applications with challenging spectral purity demands, such as 5G/6G or other advanced wireless technologies.

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Patent Abstract

The invention concerns a method for signal modulation of an input signal (S) using pulse width modulators (PWM1, PWM2), wherein the input signal (S) is modulated in said pulse width modulators (PWM1, PWM2) by means of reference signals (SR, SRPS) resulting in pulse width modulated signals with two levels (SPWM1, SPWM2), and at least one of fundamentals and harmonics of a first reference signal of said reference signals (SR) comprised in a first pulse width modulated signal of said pulse width modulated signals with two levels (SPWM1) at least partially superpose destructively with at least one of fundamentals and harmonics of a second reference signal of said reference signals (SRPS) comprised in a second pulse width modulated signal of said pulse width modulated signals with two levels (SPWM2), and a transmitter therefor.