DDS Phase Correction for Flexible Multi-Module Phase Alignment

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Solution Overview

Problem

Existing direct digital synthesizer (DDS) modules require precise simultaneous initialization of initial phase values to establish a desired phase relation, which is time-critical and challenging to achieve.

Innovation Solution

A DDS module with a phase accumulator module that includes a phase correction sub-module, allowing for adaptive phase signal adjustment based on a phase shift word (PSW), enabling a desired phase relation to be set in an arbitrary clock cycle without precise timing coordination of multiple modules.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If initial phase values of multiple DDS modules are set simultaneously within a single clock cycle to achieve desired phase relation, then phase relation precision is improved, but operation complexity and timing coordination requirements increase

Engineering Contradiction:
Improvephase relation precisionVSAvoidinitialization complexity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent divides the phase initialization process into two independent stages: (1) setting the frequency tuning word (FTW) in the frequency tuning register, and (2) setting the initial phase value in the initial phase register. This segmentation allows each parameter to be configured independently without requiring simultaneous coordination, thereby reducing operation complexity while maintaining phase relation precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by pre-calculating and storing the desired phase relation values in the initial phase register before starting the DDS operation. The phase accumulator then automatically applies this pre-set initial phase value when the system starts, eliminating the need for complex real-time timing coordination during initialization.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If simultaneous initialization of multiple DDS modules is required to establish precise phase relations, then phase relation accuracy is improved, but time consumption and coordination overhead increase

Engineering Contradiction:
Improvephase relation accuracyVSAvoidinitialization time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the configuration process into independent register writes: the FTW register is written with the frequency tuning value, and the initial phase register is written with the pre-calculated phase offset. These can be performed in any order and at different times, eliminating the time-critical simultaneous initialization requirement while maintaining phase accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The phase accumulator module automatically handles the phase relation establishment by internally adding the pre-stored initial phase value to the accumulated phase. This self-service mechanism eliminates the need for external timing coordination and reduces initialization time, as the system autonomously applies the correct phase relation once the registers are programmed.

Inventive Principle:
Principle #25Self-service

3Stability of the object's composition

If precise timing coordination is required for setting initial phase values of multiple DDS modules, then phase synchronization is improved, but system complexity and control difficulty increase

Engineering Contradiction:
Improvephase synchronizationVSAvoidcontrol coordination complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent separates the control of phase parameters into independent register operations. Each DDS module's initial phase register can be programmed independently with its desired phase offset value, and the phase accumulator will automatically maintain the correct phase relationship. This segmentation eliminates the need for complex inter-module timing coordination while preserving phase synchronization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The phase accumulator module uses feedback by continuously adding the initial phase value (stored in the initial phase register) to the accumulated phase signal. This feedback mechanism ensures that the desired phase relation is automatically maintained and synchronized across multiple DDS modules without requiring complex external control coordination.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4391385A1Direct digital synthesizer module, measurement system, and method of operating a direct digital synthesizer module
Publication Date: 2024.06.26 ROHDE & SCHWARZ GMBH & CO KG
  • EP4391385A1 patent drawingFigure 1~2
  • EP4391385A1 patent drawingFigure 3~4
  • EP4391385A1 patent drawingFigure 5

AI summary

A direct digital synthesizer (DDS) module (24) is described. The DDS module (24) comprises a phase accumulator module. The phase accumulator module comprises a clock input being configured to receive a clock signal. The phase accumulator module further comprises a frequency tuning register being configured to receive a frequency tuning word (FTW). The phase accumulator module further comprises a phase shift register being configured to receive a phase shift word (PSW). The phase accumulator module further comprises a phase increment sub-module being configured to increment a phase signal output by the phase accumulator module by a predetermined phase increment based on the clock signal and/or based on the FTW. The phase accumulator module further comprises a feedback path being configured to feed back the phase signal to the phase increment sub-module. The phase accumulator module further comprises a phase correction sub-module, wherein the phase correction sub-module is configured to adapt the phase signal fed back to the phase increment sub-module based on the phase shift word. Further, a measurement system (10) and a method of operating a direct digital synthesizer module (24) are described.