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KCC's Quizzes: AQQ229 about IP3 lab measurement



		

			

									
					    KCC
					
							

			
				
									
											
			
			
				
  •  Analog Employees  

			
			
			    	
			                    
                
				                on Mar 2, 2023 
				
			
			
		


				
		

		    		    
		    
		    	
			
   


IP3 (intercept point of order 3) is a spec one find in many RF component datasheet. It is directly linked with the linearity of a function behavior. 


More precisely, It indicates the amount of the intermodulation products of order 3 that interfere with the baseband.


The above pictures show the lab setup and a Spectrum Analyzer screenshot to measure the IP3 of a device (DUT) in the lab.


Questions:


    

  1. What are the frequencies provided by sources 1 and 2?
    2. 

  2. What is the IP3 measured in that test?
    3. 


										


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[edited by: emassa at 5:46 PM (GMT -5) on 2 Mar 2023]
				

					


				
				
		

			
						
									
									
						
						
			
			
			
			
		


        
        

					

			






	
















	

	

					



			


				
	









	
    
	

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    •  Analog Employees  
    
            
			                            
                        
                on Mar 6, 2023 5:03 PM
            
            
												
						in reply to MTF_Walker
					
									
    
	
    

		
		
    
					
    Right reaction Martin! You are not bad at all in RF!
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
				
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
			                            
                        
                on Mar 6, 2023 5:19 PM
            
            
												
						in reply to gpiarino
					
									
    
	
    

		
		
    
					
    YES! Bravo Gaetano!
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
				
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
			                            
                        
                on Mar 13, 2023 9:12 PM
            
            
					
    
	
    

		
		
    
					
    OK, it's time to publish the official answers...
    

    Solution:
    1. The 2 sources have to inject the 2 tones with close frequencies: they are visible as M1 and M2 in the SS screenshot : 1.245 GHZ and 1.255 GHz (delta = 10 MHz)
    

    2. Measured from the first source:
    M1 + (M1‐M3)/2 = ‐10.9dBm +(‐10.9dBm – (‐45.2dBm))/2 = +6.25 dBm
    Measured from the second source:
    IP3=M2 + (M2‐M4)/2 = ‐11dBm + (‐11dBm – (‐44.9dBm))/2 = +5.95dBm
    We can conclude the DUT IP3 is around +6.1 dBm
    

    3. It’s the Output IP3 (measurement taken at the output of the DUT). It is thus OIP3
    IIP3 can be deducted by OIP3 = IIP3 + Gain(in dB))
    

    Big applause to our 4 winners (and especially for the non-RF engineers)!
    

    1. Martin WALKER - ADI - Staff Field applications Engineer - Burnham, UK
    

    2. Gaetano PIARINO - ADI - Key Account Manager - Milan - Italy
    

    3. Hakan UENLUE - ADI - Technical Application Expert - Stuttgart - Germany
    

    4. Mark CEE - ADI - Snr Systems Integration Engineer - Cavite - Philippines
    

    Now, be prepared to tackle our next coming quiz AQQ230 !
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
				
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
			                            
                        
                on Mar 13, 2023 9:39 PM
            
            
												
						in reply to KCC
					
									
    
	
    

		
		
    
					
    Forgat to mention, there is an article detailing that subject (how IP3 is built) :IP3 and Intermodulation Guide | Analog Devices
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
				
						
				
				
		
		
    
			
		
    
	
    

    

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