Multi-PCA DDS Synchronization Using a Shared Reference Clock
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Solution Overview
Problem
Synchronizing multiple direct digital synthesizers (DDSs) across multiple printed circuit assemblies (PCAs) in phased array radars is challenging due to random phase differences and uncertainties in clock synchronization, especially when power is cycled, leading to inconsistent phase relationships and increased complexity and cost in master-slave configurations.
Innovation Solution
Using a copy of the reference clock signal as the synchronization signal, eliminating the need for an independent synchronization signal, and synchronizing the update signal with the reference clock time domain to ensure deterministic timing and phase continuity across DDSs, reducing the number of unique PCA designs and signal distribution complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an independent synchronization signal is used to synchronize multiple DDSs across multiple PCAs, then phase consistency can be maintained, but system complexity and cost increase due to additional signal routing and component matching requirements
Solution Approach 1:
The patent combines the reference clock signal and synchronization signal into a single signal path. The reference clock signal is distributed to all DDS devices across multiple PCAs, and these devices are configured to use this same signal for both clocking and synchronization purposes, thereby maintaining phase consistency while eliminating the need for separate synchronization routing
Solution Approach 2:
The reference clock signal serves dual functions: it acts as the clock signal for DDS operation and simultaneously serves as the synchronization signal for maintaining phase relationships across multiple PCAs. This multi-functionality eliminates the need for dedicated synchronization signal paths and reduces system complexity
2Reliability
If custom component matching is implemented to maintain synchronization across multiple PCAs, then phase relationships remain consistent, but manufacturing cost and complexity increase
Solution Approach 1:
The patent segments the synchronization function into configuration settings rather than physical component matching. Each DDS device is programmed with specific configuration parameters that enable them to automatically maintain phase relationships using the distributed reference clock, eliminating the need for manual component selection and matching during assembly
Solution Approach 2:
The patent changes the approach from physical component characteristics (requiring matched components) to programmable parameters. By configuring DDS devices with appropriate operational parameters and modes, the system achieves synchronization stability through software/configuration control rather than hardware matching, greatly simplifying manufacturing
3Reliability
If multiple unique PCA designs are used to accommodate different synchronization requirements, then DDS synchronization can be achieved, but system cost and design complexity increase
Solution Approach 1:
The patent creates a universal PCA design that can accommodate multiple DDS devices with different functions and configurations. The reference clock distribution network and DDS configuration system enable any combination of DDS devices on the same or different PCAs to be synchronized through software control rather than requiring hardware-specific designs for each synchronization scenario
4Reliability
If additional signal routing is implemented for synchronization, then phase consistency is maintained, but system cost and complexity increase
Solution Approach 1:
The patent merges the clock signal distribution and synchronization signal distribution into a single reference clock signal path. By configuring DDS devices to use the same reference clock signal for both timing and phase reference, the system maintains phase consistency without requiring separate synchronization signal routing, thereby reducing signal routing complexity
Data Source
AI summary
A radio frequency generating system comprises a synchronization board that receives an external clock signal from a clock source and generates multiple copies of the external clock signal. Each of a plurality of signal generation board receives a copy of the external clock signal from the synchronization board. Each signal generation board comprises a plurality of direct digital synthesizers that are synchronized using the external clock signal.