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LT1028 Phase Margin



		

			

									
					    KSUEDL
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Sep 16, 2022 
				
			
			
		
    

				
		
    
		    		    
		    
		    		            		        
    Category: Datasheet/Specs
    
    		        		            		    
    Product Number:  LT1028 
    
    		        		        		        
    Software Version: LTSpice XVII 17.0.35.0
    
    		    		    	
			
    I'm simulating the open loop gain/phase for an LT1028 and my result differs from the datasheet at Av=1.  I get a phase margin of almost 45 degrees and as it is not unity gain stable  it should be closer to 0 degrees per the figure on page 8 of the datasheet.  I have used 2 different methods of obtaining the OL gain and the results are the same.
    

     
    

    

     
    

    Can you shed any light on why I have a larger phase margin in the simulation than I should expect given datasheet specs?
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
			                            
                        
                on Nov 15, 2022 6:16 AM
            
            
					
      
	
      

		
		
      
					
      Hi Tim,

      Thank you for your feedback.
      It may be a case of modelling trade-off.
      The phase plot is not the usual shape for op-amps, and it seems that the modeler gave priority to getting the shape of the phase closer to the datasheet.

      We will forward your feedback to the developers.

      Thank you,
      Sham
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
				
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      
            
			                            
                        
                on Nov 15, 2022 6:16 AM
            
            
					
      
	
      

		
		
      
					
      Hi Tim,

      Thank you for your feedback.
      It may be a case of modelling trade-off.
      The phase plot is not the usual shape for op-amps, and it seems that the modeler gave priority to getting the shape of the phase closer to the datasheet.

      We will forward your feedback to the developers.

      Thank you,
      Sham
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
				
						
				
				
		
		
      
			
		
      
	
      

      

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