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AD9517-0 Recommended for New Designs
The AD9517-01 provides a multi-output clock distribution function with subpicosecond jitter performance, along with an on-chip PLL and VCO. The on-chip...
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AD9517-0 on Analog.com

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AD9517 LVPECL output interface to a fanout buffer



		

			

									
					    GuiX
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Mar 23, 2015 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hello everyone:
    
 
    I am using one AD9517-0 LVPECL output to drive a fanout buffer to convert the signal to two LDVS signals.
    
 
    In the AD9517-0 datasheet I can see this figure to interface LVPECL stages:
    
 
    
 
    On the other hand, in the datasheet of the fanout buffer, I can see this other configuration:
    
 
    
 
    My dessign follows the AD recomendation (first schematic) and incorporates R1 to R4 of the second schematic.
    
 
    Question: Should I keep the 100 Ohn resistor at the imput of the receiver (as proposed in the AD schematic)?
    
 
    Thanks in advance
    
 
    Regards
    
 
    GuiX
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 Clock Generation Devices
                
                                                    
                 Clock Generation and Distribution
                
                                                    
                 clock and timing
                
                                                    
                 AD9517-0
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Mar 23, 2015 8:00 PM
            
            
					
      
	
      

		
		
      
					
      Dear Guix,
      
 
      In the first drawing, we're assuming that the input receiver is providing its own DC biasing. Yes. you can to keep the 100 ohms across the differential pair.
      
 
      In the 2nd drawing, the Thevenin equivalent termination not only accomplishes impedance matching, but also DC-biases the input.
      
 
      However, if you want to use the LVPECL outputs on the AD9517 to drive LVDS inputs, You can do that by powering VS_LVPECL at 2.5V, and programming the amplitude bits to the min output amplitude. This will make the AD9517 LVPECL drivers compatible with LVDS in terms of amplitude and common mode voltage.
      
 
      -Paul
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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													0
							
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Mar 23, 2015 8:00 PM
            
            
					
      
	
      

		
		
      
					
      Dear Guix,
      
 
      In the first drawing, we're assuming that the input receiver is providing its own DC biasing. Yes. you can to keep the 100 ohms across the differential pair.
      
 
      In the 2nd drawing, the Thevenin equivalent termination not only accomplishes impedance matching, but also DC-biases the input.
      
 
      However, if you want to use the LVPECL outputs on the AD9517 to drive LVDS inputs, You can do that by powering VS_LVPECL at 2.5V, and programming the amplitude bits to the min output amplitude. This will make the AD9517 LVPECL drivers compatible with LVDS in terms of amplitude and common mode voltage.
      
 
      -Paul
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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