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AD8302 to be used as an RMS power detector



		

			

									
					    Vishnu
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Mar 20, 2013 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    
 
    We are presently using AD8302 in our application for VSWR measurement.
    
 
    I would like to use the same for our PA ALC application, where I would use it for RMS power measurement. Is it possible to use this using the Vmag pin.
    
 
    Is yes, please tell me what I should do to the Vph pin (grounded or terminated to 50E...)
    
 
    Regards,
    Vishnu
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
			                            
                        
                on Mar 22, 2013 8:39 PM
            
            
					
      
	
      

		
		
      
					
      Hi Vishnu,
      
 
      Unfortunately, I do not think this will work because of the dynamic range of the internal logs and the voltage rails of the output stage (which are ground and 1.8V).
      
 
      What you will probably see if you do this is the Vmag pin railed to 1.8V.  Please see Figure 7 in the datasheet and the paragraph above that figure.
      
 
      Again, I would recommend a stand alone log amp or RMS detector.  Is there a reason you'd like to use the AD8302 in this way?
      
 
      Thanks,
      
 
      Joel
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      
            
			                            
                        
                on Mar 22, 2013 8:39 PM
            
            
					
      
	
      

		
		
      
					
      Hi Vishnu,
      
 
      Unfortunately, I do not think this will work because of the dynamic range of the internal logs and the voltage rails of the output stage (which are ground and 1.8V).
      
 
      What you will probably see if you do this is the Vmag pin railed to 1.8V.  Please see Figure 7 in the datasheet and the paragraph above that figure.
      
 
      Again, I would recommend a stand alone log amp or RMS detector.  Is there a reason you'd like to use the AD8302 in this way?
      
 
      Thanks,
      
 
      Joel
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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