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AD9546 Recommended for New Designs
The AD9546 incorporates digitized clocking technology that efficiently transports and distributes clock signals in systems. Digitized clocking allows the...
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AD9546 on Analog.com

AD9083 Recommended for New Designs
The AD9083 is a 16-channel, 125 MHz bandwidth, continuous time S-? (CTSD) ADC. The device features an on-chip, programmable, single-pole antialiasing filter...
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AD9083 on Analog.com

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Locking on 125MHz with  clock qualifier

		
	
				

			

									
					    Mikelson
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jun 4, 2025 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user seeks to generate a 10ms periodic signal for the AD9083 SYSREF input using the AD9546, with a 125MHz clock and a jittery qualifier signal on M2. The solution involves configuring OUT0B in N-shot mode and using M2 to trigger the 10MHz pulse, ensuring it aligns with the 125MHz clock cycle. The AD9546 can achieve this by setting M2 to generate a DIST0 NSHOT REQUEST, as demonstrated in a quick test on the eval board.
                        	    
    
                
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    Category: Hardware
    
    		        		            		    
    Product Number:  AD9546 
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hi,
    

    in our application, we have an AD9546 driving an AD9083 ADC. The AD9546 is receiving a 125MHz clock by M3 input, and a clock qualifier on M2. The qualifier is valid on the rising edge of the 125MHz clock and should be used to generate a 10ms periodic signal for the AD9083 SYSREF input (while the 125MHz are converted to 250MHz as clock input for AD9083).
    Due to the jitter on the qualifier signal, using it directly does not really work, so my question is if it is possible to use it as a "qualifier" signal, which simply indicates the clock cycle of the 125MHz which completes the 10ms period.
    

    Thanks in advance!
    
			
    
			
									
		                             
                        

    
    
                                            
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jun 17, 2025 11:27 AM
            
            
						
			            		
      
		
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      HI,
      

      sorry for getting back to you so late.
      

      The AD9546 can generate for example OUT0A=250MHz and OUT0B=10MHz and have OUT0B acting as a SYSREF because OUT0B is phase aligned to OUT0A. It is like a SYSREF in continuous mode. You can also set OUT0B in N-shot mode.
      

      Now, if I understand you correctly, you want to generate OUT0B=10MHz when M2 is high. Look at page 101 in the AD9546 data sheet: 
      

       
      

      So if you set OUT0B to work in N-shot mode and then you set M2 to generate a DIST0 NSHOT REQUEST, you should be able to accomplish what you want.
      

        
      

      I made a quick program and I supplied on the AD9546 eval board M2 pin a 1.8V CMOS, 1kHz clock and I could see OUT0B=10MHz pulse coming out after M2 pin was going high. So it seems to me this can do what you seem to want.
      

      Petre
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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