Polar Modulator Output Filters for Absorbing Reflected Harmonics

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Solution Overview

Problem

Polar transmitters face inefficiencies due to reflected harmonic components interfering with the RF carrier and causing power dissipation in the power transistors, leading to reduced drain efficiency and potential damage from large voltage spikes or high currents when using low-pass filters alone.

Innovation Solution

A combination of a harmonic low-pass filter and an absorptive high-pass filter is used in the output filter network to pass the fundamental RF component while absorbing higher harmonics, preventing interference and reducing power dissipation, and mitigating damage from voltage spikes or high currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a low-pass filter is used to prevent harmonic components from reaching the load, then only the fundamental component passes to the load, but harmonic components are reflected back toward the SMPA output causing interference and large voltage pulses

Engineering Contradiction:

Improveharmonic interference at loadVSAvoidreflected harmonics causing voltage spikes and interference

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent applies absorptive filters that convert harmful reflected harmonic energy into useful heat dissipation. The absorptive high-pass filter and absorptive band-pass filter absorb harmonic components that would otherwise be reflected back to cause voltage spikes and interference, transforming the harmful reflected energy into beneficial heat that is safely dissipated.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces absorptive filter networks as intermediary elements between the SMPA output and the load. These filters act as mediators that intercept harmonic components before they can be reflected back to cause damage, providing a safe pathway for harmonic energy dissipation without allowing it to interfere with the fundamental RF carrier.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If reflected harmonic components are allowed to return to the SMPA output, then the SMPA operates over a wider tuning range, but power dissipation increases and drain efficiency decreases

Engineering Contradiction:

Improvetuning rangeVSAvoidpower dissipation in power transistors

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts harmful harmonic components from the SMPA output using absorptive filters before they can be reflected back and cause energy loss. By taking out the harmonic components through dedicated absorptive filter networks, the system maintains wide tuning range capability while preventing the energy dissipation and drain efficiency degradation that would result from reflected harmonics.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If reflected harmonic components interfere with the RF carrier, then the waveform distortion increases, but the fundamental component can still reach the load

Engineering Contradiction:

Improvefundamental component transmissionVSAvoidwaveform distortion

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The absorptive filters convert the harmful effect of waveform distortion into a beneficial outcome by absorbing harmonic components before they can interfere with the fundamental RF carrier. This transformation ensures that the fundamental component reaches the load cleanly without distortion while the harmonic energy is safely dissipated as heat in the absorptive filter networks.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This configuration enhances the operational efficiency of the polar transmitter by minimizing harmonic interference and power dissipation, improving drain efficiency and preventing component damage, while allowing wider tuning ranges and effective operation over a broader frequency range.

Implementation Method 1

an absorptive high-pass filter connected in parallel with the harmonic low-pass filter, wherein the harmonic low-pass filter and the absorptive high-pass filter pass the fundamental component of the modulated RF carrier to the load while absorbing higher harmonics

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

a harmonic low-pass filter connected in parallel with an absorptive high-pass filter, wherein the harmonic low-pass filter and the absorptive high-pass filter pass the fundamental component of the modulated RF carrier to the load

Methodology Applied

Scientific EffectFiltering (electronic): Filter (electronic)

Data Source

PatentUS11949546B2Harmonic filters for polar modulators

Publication Date: 2024.04.02 ERIDAN COMMUNICATIONS D O O

AI summary

A modulated RF carrier produced at the output of the polar transmitter's switch-mode power amplifier (SMPA) is conveyed to an output filter network comprising a harmonic low-pass filter (LPF) connected in parallel with an absorptive high-pass filter (HPF). Together the harmonic LPF and absorptive HPF pass the fundamental component of the modulated RF carrier to the polar transmitter's load while also absorbing higher harmonic components that would otherwise be undesirably reflected back toward the output of the SMPA.