Wideband Spectrum Analyzer With Switchable Filters for Image Rejection

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Solution Overview

Problem

Existing signal and spectrum analyzers require multiple devices to cover different applications, leading to high costs and manual effort in test procedures due to the limited bandwidth capacity of each device.

Innovation Solution

A wideband spectrum analyzer with a single instrument that includes a series connection of filter modules with highpass and lowpass filters, allowing independent selection and control of these filters to achieve flexible bandwidth settings, image suppression, and spur rejection, while using a bypass-line for direct sampling of certain frequency bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple signal and spectrum analyzers are used to cover different applications, then the bandwidth capacity is sufficient, but the overall costs increase and manual effort in test procedures increases

Engineering Contradiction:
Improvebandwidth capacityVSAvoidnumber of devices
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a single spectrum analyzer that can function across multiple bandwidth ranges (e.g., 100 MHz, 1 GHz, 3 GHz, 10 GHz) by integrating multiple filter modules with different bandwidth characteristics. The system uses switchable filter configurations to adapt to different application scenarios, eliminating the need for multiple separate analyzers and reducing both cost and operational complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple signal and spectrum analyzers are used to cover different applications, then the bandwidth capacity is sufficient, but the manual effort in test procedures increases

Engineering Contradiction:
Improvebandwidth capacityVSAvoidmanual effort
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The system employs dynamic filter selection where the filter module configuration can be changed on-the-fly based on the measurement requirements. Switches allow rapid reconfiguration between different bandwidth settings without physical device changes, enabling automated test sequences and reducing manual intervention for connecting different analyzers to the device under test.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If filter modules are added to achieve flexible bandwidth settings, then the adaptability improves, but the device complexity increases

Engineering Contradiction:
Improvebandwidth setting flexibilityVSAvoidfilter module configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system divides the filtering function into separate, modular filter modules, each designed for a specific bandwidth range. These modules can be independently selected and combined through switchable configurations, allowing the system to achieve multiple bandwidth capabilities without requiring a single complex filter design. Each module remains relatively simple in structure while the system as a whole gains versatility.

Inventive Principle:
Principle #1Segmentation

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 solution provides a single analyzer with maximum bandwidth and high spur and image rejection, reducing the need for multiple devices and minimizing manual effort by enabling flexible bandwidth settings and efficient signal processing across various applications.

Implementation Method 1

The first filter module comprises first switches and several different highpass filters being arranged in a parallel connection, wherein the first switches are configured to selectively connect one of the highpass filters with an input of the first filter module and an output of the first filter module. The second filter module comprises second switches and several different lowpass filters being arranged in a parallel connection

Methodology Applied
Scientific EffectFiltering: Filter (electronic)

Data Source

PatentEP4033258B1Wideband spectrum analyzer
Publication Date: 2025.10.01 ROHDE & SCHWARZ GMBH & CO KG
  • EP4033258B1 patent drawingFigure 1
  • EP4033258B1 patent drawingFigure 2

AI summary

A wideband spectrum analyzer (10) is disclosed that has good image suppression and dynamic range. The wideband spectrum analyzer (10) comprises at least one signal input (12), and at least one signal channel (14) with a first filter module (16) and a second filter module (18). The first filter module (16) and the second filter module (18) are connected with the at least one signal input (12) downstream of the at least one signal input (12) in a series connection. The first filter module (16) comprises first switches (32, 34). The first filter module (16) comprises several different highpass filters (36) being arranged in a parallel connection. The first switches (32, 34) are configured to selectively connect one of the highpass filters (36) with an input (38) of the first filter module (16) and an output (40) of the first filter module (16). The second filter module (18) comprises second switches (42, 44). The second filter module (18) comprises several different lowpass filters (46) being arranged in a parallel connection. The second switches (42, 44) are configured to selectively connect one of the lowpass filters (46) with an input (48) of the second filter module (18) and an output (40) of the second filter module (18).