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HMC704 Last Time Buy
The HMC704 has been designed for the best phase noise and lowest spurious content possible in an integrated synthesizer. Fabricated in a SiGe BiCMOS process...
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HMC704 on Analog.com

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phase noise

		
	
				

			

									
					    Silversir
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jan 15, 2025 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  HMC704 
    
    		        		    		    
    
		    		    
		    			
    
			    
    Why dose the phase noise of PLL degrade by 20logN ? I still don't understand,Plz.
    
			
    
			
									
		                             
                        

    
    
                                            
                 hardware
                
                                                    
                 phase noise
                
                                                    
                 Fractional-N PLL
                
                                                    
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jan 27, 2025 12:51 PM
            
            
						
			            		
      
		
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      Hi,
      

      The phase noise degradation of 20LogN is an inherent characteristic of a PLL system. Where N is the multiplication factor of the Fpfd frequency. 
      

      The reference has an associated phase deviation which produces phase noise power. This phase noise is increased logarithmically by a factor of 20logN when multiplied by the reference. 
      

      This will always be a factor in the overall phase noise within the PLL. I hope that answers your question. But if you are confused about anything in particular, please feel free to ask.
      

      Thanks,
      

      Kieran 
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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