DDS Signal Generator Architecture Without Down-Mixer Complexity

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Solution Overview

Problem

Current signal generators require complex and costly down mixers to generate lower frequency ranges, leading to high component expenditure, space requirements, and power consumption, while also limiting frequency resolution and increasing manufacturing costs.

Innovation Solution

A signal generator design that eliminates the need for a down mixer by directly connecting the output of a DDS signal source to a level-adjustment device, reducing circuit complexity and allowing for a more compact and power-efficient design with improved phase-noise properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a down mixer is used to generate lower frequency ranges, then the frequency range can be extended, but the device complexity and manufacturing costs increase

Engineering Contradiction:

Improvefrequency rangeVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the down mixer component from the signal generator architecture. By using a DDS (Direct Digital Synthesis) signal source that can directly generate lower frequency ranges without requiring frequency mixing, the patent removes the complex down mixer circuitry while maintaining the ability to provide extended frequency coverage through the DDS's inherent frequency synthesis capabilities

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the analog mixing mechanism (down mixer) with a digital synthesis approach (DDS). Instead of using analog frequency mixing operations to generate lower frequencies, the system uses digital signal processing to directly synthesize the desired frequency outputs, thereby eliminating the need for complex analog mixing circuits

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a down mixer is used to generate lower frequency ranges, then the frequency range can be extended, but the manufacturing costs increase

Engineering Contradiction:

Improvefrequency rangeVSAvoidmanufacturing costs

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

By extracting and removing the down mixer component, the patent reduces the bill of materials and assembly requirements. The DDS-based architecture eliminates expensive analog mixing components and associated calibration requirements, thereby reducing manufacturing costs while maintaining extended frequency range capability through digital synthesis

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental operating parameters from analog frequency mixing to digital frequency synthesis. This parameter change allows the system to achieve the same frequency range extension function through digital means, which are more cost-effective to manufacture and program than analog mixing circuits

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If frequency division is used to generate lower frequencies, then the frequency range can be extended, but the number of filters required increases

Engineering Contradiction:

Improvefrequency rangeVSAvoidnumber of filters

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent removes the cascade of frequency dividers and associated low-pass filters from the architecture. The DDS signal source directly generates the required frequency outputs without needing intermediate division stages, thereby eliminating the need for multiple filters while maintaining the ability to provide extended frequency coverage

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The DDS architecture provides continuous frequency synthesis capability across the entire frequency range without discontinuous division stages. This continuous digital synthesis approach eliminates the need for multiple filter stages that would be required in a divided architecture, as the DDS can directly output any frequency within its range

Inventive Principle:

Principle #20Continuity of useful action

4Adaptability or versatility

If a down mixer is used to generate lower frequency ranges, then the frequency range can be extended, but the space requirements increase

Engineering Contradiction:

Improvefrequency rangeVSAvoidspace requirements

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

By extracting and eliminating the down mixer and its associated local oscillator and filtering components, the patent significantly reduces the physical footprint of the signal generator. The integrated DDS architecture consolidates multiple functions into a single chip or module, thereby reducing space requirements while maintaining extended frequency range capability

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8044725B2Signal generator with directly-extractable DDS signal source

Publication Date: 2011.10.25 ROHDE & SCHWARZ GMBH & CO KG

AI summary

A signal generator including a DDS-signal source that is configured to operate according to the principle of direct digital synthesis (DDS), and a PLL signal synthesizer that is configured to operate according to the principle of phase locked loop (PLL) using an output signal from the DDS-signal source as a reference signal. The DDS-signal source can be connected via a direct connection, without further frequency division or mixing, directly to an output of the signal generator or directly to a level-adjustment device of the signal generator in order to generate a portion of an overall frequency range of an output signal of the signal generator.