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AD8117 frequency response



		

			

									
						JeffPaul
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on Feb 8, 2017 
				
			
			
		


				
		

		    		    
		    
		    	
			
We plan to use the AD8117's crosspoint capability for muxing differential signal in one input channel to any of the 32 output channel.

 
However, the output load is essentially a front end of a switch cap filter and we are wondering if that might change the frequency response in any way?

 
I tried looking at the SPICE model for the AD8117 but there is none. Is there an equivalent model we can use instead?

								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	

		
	















	

	

					



			








	
	
	
	



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                                 Analog Employees 
                                
                            
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                on Feb 12, 2017 10:38 PM
            
            
					
    
	
    

		
		
    
					
    Hi.
    
 
    What's the capacitance did you use for your switched cap filter? If you require a -3dB BW of 420MHz for a Rload (diff) of 200 ohms, then you need to have a cap of 11.9uF. If this cap was used, then the frequency response will not be affected but if you use more than or less than ~12uF then it would give a different freq. response. If you also use different frequency and Rload, then the response would also be different. For series and parallel switched cap filter, use this formula to get the correct cap -- R=T/C where T is equal to 1/frequency.
    
 
    As to the SPICE model, we don't have any for our Analog Crosspoint switches.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
						
				
				
		
		
    
			
		
    
	
    

    

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													0
							
			
				
									
							        
            
                                                                                                        
      
                            
    • 
                                 Analog Employees 
                                
                            
      • 
                        
     
                                                           			
			                            
                        
                on Feb 12, 2017 10:38 PM
            
            
					
    
	
    

		
		
    
					
    Hi.
    
 
    What's the capacitance did you use for your switched cap filter? If you require a -3dB BW of 420MHz for a Rload (diff) of 200 ohms, then you need to have a cap of 11.9uF. If this cap was used, then the frequency response will not be affected but if you use more than or less than ~12uF then it would give a different freq. response. If you also use different frequency and Rload, then the response would also be different. For series and parallel switched cap filter, use this formula to get the correct cap -- R=T/C where T is equal to 1/frequency.
    
 
    As to the SPICE model, we don't have any for our Analog Crosspoint switches.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
						
				
				
		
		
    
			
		
    
	
    

    

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