Thread Details

  • State Verified Answer
  • Replies 5 replies
  • Subscribers 22 subscribers
  • Views 2200 views
  • Users 0 members are here
Options
 
Related Content

        

            Post
             Go back to editing
        

    

    


    

    









		


















	
	
			
	
			
		
	
	
		

	    
	    
	    		
Can I use analog switch as chopper switches

		
	
				

			

									
					    JohnTexas
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Oct 21, 2017 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
		    			
    
			    
    I am building a chopper amplifier to remove 1/f noise. I used ADG1436YRUZ as the modulator for the differential input; then modulated the differential signal is amplified and converted to single ended signal; then this signal and its inverted signal is passed through ADG1419BRMZ for demodulation. For current board, it still has 1/f noise, (around 1Hz). I will improve the clock distribution in next version. But I don't see any schematic mentioning using ADG analog mux as chopper switch. All of the article talking about using discrete NMOS for chopper switches. Is there problem for me to use ADG for this purpose?
    
			
    
			
									
		                             
                        
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



Parents
	
      
	

    • 
	
      



	
		
	
	



      
	
      
		
      
							
					
      
		
      
		    
		    		    
			
				
									
							        
			
			
			
        
            
						
                            
            
            				
            
                on Oct 26, 2017 3:00 PM
            
            
						
			            		
        
		
										0
					
	
        

		
		
        
		
        
                                
                                                            
        
					
        David:
        
 
           I can not use ADG1208 family, even their charge injection is very small compared with ADG733. because their resistance is too high 120 Ohm which gives 1.4nV/sqrt(Hz) for one side and about 2nV/sqrt(Hz) for noise summation of both sides while it need to below 0.5nV/sqrt(Hz). In addition, the larger resistance, the larger serial voltage which will be developed from imbalanced charge current. ADG733 has 2.5 Ohm while only 3PC charge injection , so it is the best candidate.
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

        • 

	
      



Reply

        


      • 
	
        



	
		
	
	



        
	
        
		
        
							
					
        
		
        
		    
		    		    
			
				
									
							        
			
			
			
          
            
						
                            
            
            				
            
                on Oct 26, 2017 3:00 PM
            
            
						
			            		
          
		
										0
					
	
          

		
		
          
		
          
                                
                                                            
          
					
          David:
          
 
             I can not use ADG1208 family, even their charge injection is very small compared with ADG733. because their resistance is too high 120 Ohm which gives 1.4nV/sqrt(Hz) for one side and about 2nV/sqrt(Hz) for noise summation of both sides while it need to below 0.5nV/sqrt(Hz). In addition, the larger resistance, the larger serial voltage which will be developed from imbalanced charge current. ADG733 has 2.5 Ohm while only 3PC charge injection , so it is the best candidate.
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

          • 


        


Children
	
        No Data