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Cascading two AD55x7's for bit resolution doubling



		

			

									
					    e-asphyx
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Dec 4, 2016 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Is it possible to use one AD55x7 DAC as reference source for second one to produce higher bit resolution? What drawbacks this solution may have?
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 Precision D/A Converters
                
                                                    
                 Multiplying Current Output D/A Converters
                
                                                    
                 ad5557
                
                                                    
                 ad5547
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Dec 8, 2016 1:18 PM
            
            
					
      
	
      

		
		
      
					
      Hi,
      
 
      That is an interesting thought. Are you planning on a full +/- Vref input +/- Vref 2x output? In theory, this is possible but this is not usually done in practice. Cascading two DACs has their own drawbacks:
      
 
        
  
      • The noise of the first DAC will be added to the second DAC which will result in higher noise levels.
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      • Output slew rate of the first DAC should be taken into consideration because the output of the first DAC will be the reference of the second DAC. Note that the value of the first DAC must have settled to its desired value to be able for the second DAC to produce the correct voltage level.
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      • The AD55X7 would require a couple of op amps so cascading them together would require you to have at least four additional components.
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      If you would share your application or motivation for a higher resolution DAC, we may be able to recommend a proper DAC that would match your application needs.
      
 
      Regards,
      
 
      Mark
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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