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ADL5801 Recommended for New Designs
The ADL5801 uses a high linearity, doubly balanced, active mixer core with integrated LO buffer amplifier to provide high dynamic range frequency conversion...
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ADL5801 on Analog.com

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want clarity on the impedance of the RF and LO inputs.

		
	
				

			

									
					    ddurfeeengineer
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 14, 2025 
				
			
			
		
    
		
		                    	    
    
        	    
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                The user wants to drive an LVDS oscillator signal into the LO of a mixer with a 50 ohm differential input. The eval board uses 50 ohm traces, suitable for single-ended drive. For differential LVDS drive, a 2:1 balun or ac-coupling one side of the LVDS signal to LOIP and LOIN to ground is recommended.
                                    
    
                    
    
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    Product Number:  ADL5801  
    
    		        		    		    
    
		    		    
		    			
    
			    
    I want to drive a signal based on an LVDS oscillator into the LO of this mixer.  The data sheet says 50 ohms differential in text and when it talks about the inputs it says they are 50 ohms.  The eval board seems to have traces for 50 ohms to ground.  So, is this 100 ohms differential (so I can drive directly into the differential input) or is it 50 ohms and I need a 2:1 impedance matching transformer?
    
			
    
			
									
		                             
                        

    
    
                                            
                 single
                
                                                    
                 hardware
                
                                                    
                 RF Mixers
                
                                                    
                 rf & microwave
                
                                                    
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Nov 17, 2025 6:15 PM
            
            
						
			            		
      
		
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      The LO input port has a differential input impedance of 50 ohms. The evaluation board was designed to offer various LO configuration options (differential input, single external input to balun to differential input, Single-ended input with ac-coupling capacitors). This presents challenges for the pcb trace design, that is, whether and which traces should be 25 ohms or 50 ohms. The board was designed with 50 ohm traces. That suits single ended drive through an ac-coupling capacitor with LOIN ac-coupled to ground. 
      

      If you want to drive the LO port differentially with and LVDS signal which is differential and has a characteristic impedance of 100 ohms, then you would ideally have two side-by-side 50 ohm traces, a 2:1 balun, and two 25 ohm traces into LOIN/LOIP. A simpler approach would be to just take one side of the LVDS signal, ac-couple it into LOIP and then ac-couple LOIN to ground. In this case, all of your traces would be 50 ohms. 
      

      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
				
				
				
		
		
      
			
		
      
	
      

      

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