ASK Demodulation Circuit with High-Pass Feedback for Noise Rejection

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Solution Overview

Problem

Existing demodulation systems using amplitude shift keying (ASK) face interference from high-frequency noise signals, which distort the desired signal and prevent accurate transmission in inductively coupled plug-and-socket connections.

Innovation Solution

An electronic circuit with a rectifier, filter, voltage matching network, and a feedback network with a high-pass characteristic is used to suppress high-frequency noise components, ensuring accurate demodulation by amplifying small signal differences and compensating for noise-induced hysteresis in the comparator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a comparator with hysteresis is used for demodulation, then the desired signal can be detected, but high-frequency noise components cause inaccurate detection

Engineering Contradiction:

Improvesignal detection accuracyVSAvoidhigh-frequency noise interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The circuit segments the signal processing into distinct frequency bands using multiple filters. A first filter handles low-frequency components while a second filter handles high-frequency components, allowing separate processing and recombination to eliminate noise interference while preserving signal integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary signal path that processes high-frequency noise components separately through a second filter before recombination. This intermediary processing allows the noise to be managed independently from the main signal path, preventing it from causing inaccurate comparator detection

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If high slew rate switching means are used for modulation, then signal transmission speed is improved, but high-frequency noise components are generated

Engineering Contradiction:

Improvesignal transmission speedVSAvoidhigh-frequency noise signals

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful high-frequency noise generated by fast switching into a manageable signal component. By using a second filter to specifically process high-frequency components and then recombining them with the main signal path, the noise is transformed from a detrimental factor into a controlled element that can be separated and managed independently

Inventive Principle:

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

Solution Approach 2:

The circuit dynamically adapts to different frequency components by using multiple parallel filter paths. The first filter processes low-frequency signal components while the second filter processes high-frequency components, allowing the system to dynamically handle both the useful signal and the noise-generated high-frequency content separately before recombination

Inventive Principle:

Principle #15Dynamics

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 proposed solution effectively damps noise signals, ensuring error-free transmission by matching the feedback network's high-pass characteristic to the noise frequencies, thereby improving the accuracy of signal reconstruction and initialization for successful data transmission.

Implementation Method 1

a rectifier (3) which passes only one polarity of the carrier signal

Methodology Applied

Scientific EffectRectification: Diode

Implementation Method 2

at least one filter (4), subsequent to the rectifier, for the suppression of at least one frequency range of the carrier signal

Methodology Applied

Scientific EffectElectronic filtering: Filter (electronic)

Implementation Method 3

a feedback network connected in parallel with comparator, wherein the feedback network connects one of the two inputs of the comparator with the output of the comparator, and wherein the feedback network comprises high-pass characteristic

Methodology Applied

Scientific EffectHigh-pass filtering: Filter (electronic)

Data Source

PatentUS9031121B2Electronic circuit and method for recovering desired signals from carrier signals by demodulation as well as a modem

Publication Date: 2015.05.12 ENDRESS HAUSER CONDUCTA GESELLSCHAFT FUER MESS UND REGELTECHNIK MBH CO KG

AI summary

An electronic circuit comprising a rectifier which passes only one polarity of a carrier signal; at least one filter, subsequent to the rectifier, for the suppression of at least one frequency range of the carrier signal; a voltage matching network, subsequent to the filter, which is embodied so that it matches the voltage of the desired signal, and leads to one of the two inputs of a comparator, wherein an output of the comparator is switched, depending on the difference between the two inputs, and a feedback network connected in parallel with the comparator, wherein the feedback network connects one of the two inputs of the comparator with the output of the comparator, the feedback network comprises a high-pass characteristic. The invention furthermore comprises a method for the recovering of desired signals from a carrier signal by demodulation and a modem.