Variable Attenuator Switching Circuit Phase Compensation

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Solution Overview

Problem

Existing switching circuits face challenges with narrow band resonance due to parasitic elements, leading to phase changes, which limit their operational bandwidth.

Innovation Solution

A variable attenuator design where a first switch is connected in parallel with a circuit element and a second switch is connected in series, with both switches alternately turned on and off, and their parasitic capacitance or inductance is balanced to equalize parasitic effects in different states, reducing phase changes across a wide band.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resonance of inductive element and parasitic capacitance is used to cancel parasitic element influence, then phase change is compensated, but the bandwidth becomes narrow

Engineering Contradiction:
Improvephase change compensationVSAvoidbandwidth
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the configuration parameters of the switching circuit by introducing a specific circuit element connected in parallel with the switch. This modifies the impedance characteristics and resonant behavior of the circuit, allowing phase change compensation to be achieved across a broader frequency range rather than at a single resonant frequency, thus expanding bandwidth while maintaining reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary circuit element (connected in parallel with the switch) that acts as a mediator to counterbalance the parasitic capacitance. This intermediary component works together with the parasitic element to achieve phase compensation without requiring the narrow band resonance condition, thereby resolving the contradiction between phase stability and bandwidth

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively reduces phase changes over a wide band by ensuring equal parasitic effects in both switch states, enhancing the operational bandwidth of the switching circuit.

Implementation Method 1

the second switch has a parasitic capacitance or a parasitic inductance set in such a way that a parasitic capacitance or a parasitic inductance, respectively, occurring at the parallel circuit in a first state in which the first switch is controlled to be off and the second switch is controlled to be on and a parasitic capacitance or a parasitic inductance, respectively, occurring at the second switch in a second state in which the first switch is controlled to be on and the second switch is controlled to be off are equal to each other

Methodology Applied
Scientific EffectParasitic capacitance: Parasitic Capacitance

Implementation Method 2

the second switch has a parasitic capacitance or a parasitic inductance set in such a way that a parasitic capacitance or a parasitic inductance, respectively, occurring at the parallel circuit in a first state in which the first switch is controlled to be off and the second switch is controlled to be on and a parasitic capacitance or a parasitic inductance, respectively, occurring at the second switch in a second state in which the first switch is controlled to be on and the second switch is controlled to be off are equal to each other

Methodology Applied
Scientific EffectParasitic inductance: Parasitic Capacitance

Data Source

PatentEP3758225B1Switching circuit and variable attenuator
Publication Date: 2023.05.03 MITSUBISHI ELECTRIC CORP
  • EP3758225B1 patent drawingFigure 1~3
  • EP3758225B1 patent drawingFigure 4A~6B
  • EP3758225B1 patent drawingFigure 7A~9

AI summary

A first switch (4) is connected in parallel with a circuit element (3). A second switch (5) is connected in series with a parallel circuit constituted by the circuit element (3) and the first switch (4). The first switch (4) and the second switch (5) alternately perform on-off operation.