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ADMV4420 Recommended for New Designs
The ADMV4420 is a highly integrated, double balanced, active mixer with an integrated fractional-N synthesizer, ideally suited for next generation K band...
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Strange spurs on the output of ADMV4420

		
	
				

			

									
					    AAmiri
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Aug 23, 2024 
				
			
			
		

		
		                     
				
        		

		    
		    		    

		      		            		        
Category: Hardware

    		        		            		    
Product Number:  ADMV4420  

    		        		    		    

		    		    
		    			

			    
Hi all, 


I'm injecting a RF frequency into the 4420 and when monitoring the IF output closely, there are some spurs that appear to be of harmonics of sorts. This happens when at a specific  RF frequency, the narrower it gets, the spurs start to get closer to the carrier. Has anyone else seen these? What could be the reason? I suspect it has something to do with the 50 MHz REF mixing in the 4420 somehow? I have tested the 4420 Eval board and the spurs are there too but their levels are slightly lower. 




Any ideas as to how these spurs can be lowered?




 




Cheers,


AA

			

			
									
		                             
                        

    

                                            
                 Microwave and mmWave Tx/Rx
                
                                                    
                 hardware
                
                                                    
                 ADMV4420
                
                                                    
                 RF Integrated Transceivers
                
                                
            

    
    
		


				
				        
        		

			
						
									
												
			
			
                        
                                    
                        
                                                    
                        
            
			            
						
						
			
			
			
			
		


        
        
        
    
					

			





















	

	

					



			


				
	









	
    
	

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Sep 6, 2024 3:08 PM
            
            
						
			            		
    
		
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    Here's a few things to try:
    

      

    1. Check the RFIN signal is clean coming into the ADMV4420; if not, find another signal generator that is clean.
      2. 

    2. Connect the RFIN port of the ADMV4420 eval board to the spectrum analyzer and look for the VCO signal (half the LO frequency), check to see if the spurs are present on the VCO feedthrough signal.
      3. 

    3. If the spurs are present on the VCO feedthrough signal, then consider it might be coming from power supply, so either measure supply baseband noise or try different supply.
      4. 

    4. If possible, try to synchronize the spectrum analyzer to the 50MHz XTAL on the ADMV4420 eval board.
      5. 

    5. If possible, remove the XTAL, drive the ADMV4420 eval board with single-ended source that has the 10MHz reference synchronized to the spectrum analyzer.
      6. 

    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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