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AD9213 Recommended for New Designs
The AD9213 is a single, 12-bit, 6 GSPS/10.25 GSPS, radio frequency (RF) analog-to-digital converter (ADC) with a 6.5 GHz input bandwidth. The AD9213 supports...
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ADC Noise floor Understanding

		
	
				

			

									
					    Ramarao
					
							

            
            			
				
									
											
			
			
				
  •  Analog Employees  

			
			
			    	
			                    
                
				                on Dec 4, 2024 
				
			
			
		

		
		                     
				
        		

		    
		    		    

		      		            		        
Category: Datasheet/Specs

    		        		            		    
Product Number:  AD9213  

    		        		    		    

		    		    
		    			

			    
Hello,


I have captured ADC Output IQ samples and trying to come up with the noise floor measurement and relating to the noise figure.


I have plotted these IQ data using Visual Analog tool and the plot is below.


 


I'm not clear how the Average Bin noise is calculated, can you please help me out? If i look at the noise floor, it is about -125dBFS/Hz. However, Average Bin noise is calculated as -133.768dBFS/Hz. How this is derived?


The IQ is captured at 245.76MSPS for 20ms duration.

			

			
									
		                             
                        

    

                                            
                 Datasheet/Specs
                
                                                    
                 ADC Output Noise floor
                
                                                    
                 High Speed A/D Converters >10 MSPS
                
                                                    
                 Standard High Speed A/D Converters
                
                                                    
                 ad9213
                
                                
            

    
    
		


				
				        
        		

			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		


        
        
        
    
					

			





















	

	

					



			








	
	
	
	



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                on Dec 5, 2024 2:36 PM
            
            
						
			            		
      
		
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      Hello,
      

      The equivalent NF of the ADC can be determined as follows:
      

      1) With a small (or no) signal applied to the ADC such that ADC noise floor is not jitter limited...........,determine the noise floor in dBFS/Hz from the FFT.  In your plot, it is -147.7 dBFS/Hz.  

      2) Calculate what the full-scale input power (i.e. resulting in 0 dBFS reading on FFT) of a sine wave is in dBm while assuming perfect matching).  This is often referred to as PIN_0dBFS. In the case of the AD9213 with a 1.4 Vpp input and 50 ohm RIN, the PIN_0dBFS is  6.9 dBm (i.e. 4.9 mW).

      3) Normalize the ADC noise floor to dBm/Hz (i.e.    = PIN_0dBFS-ADC_Noise_Floor).   The noise floor in dBm/Hz for your plot is -140.8 dBm/Hz ( = 6.9 dBm - 147.7 dBFS/Hz).

      4) The Noise Figure (NF) is the additive noise above thermal noise floor of -174 dBm/Hz at 25 C.  For your plot, the NF = 33.2 dB  (i.e = -140.8 dBm/Hz - (-174 dBm/Hz).
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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                on Dec 5, 2024 2:36 PM
            
            
						
			            		
        
		
										0
					
	
        

		
		
        
		
        
                                
                                                            
        
					
        Hello,
        

        The equivalent NF of the ADC can be determined as follows:
        

        1) With a small (or no) signal applied to the ADC such that ADC noise floor is not jitter limited...........,determine the noise floor in dBFS/Hz from the FFT.  In your plot, it is -147.7 dBFS/Hz.  

        2) Calculate what the full-scale input power (i.e. resulting in 0 dBFS reading on FFT) of a sine wave is in dBm while assuming perfect matching).  This is often referred to as PIN_0dBFS. In the case of the AD9213 with a 1.4 Vpp input and 50 ohm RIN, the PIN_0dBFS is  6.9 dBm (i.e. 4.9 mW).

        3) Normalize the ADC noise floor to dBm/Hz (i.e.    = PIN_0dBFS-ADC_Noise_Floor).   The noise floor in dBm/Hz for your plot is -140.8 dBm/Hz ( = 6.9 dBm - 147.7 dBFS/Hz).

        4) The Noise Figure (NF) is the additive noise above thermal noise floor of -174 dBm/Hz at 25 C.  For your plot, the NF = 33.2 dB  (i.e = -140.8 dBm/Hz - (-174 dBm/Hz).
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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