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ADAU1701 Lock-in amplifier


		

			

									
						karolina_1
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on Sep 17, 2018 
				
			
			
		


				
		

			
Hi,




I would like to design a "Lock-in amplifier" using ADAU1701 DSP chip. Lock-in uses a technique known as phase sensitive detection to single out the component of the signal at a specific frequency. Signals at other frequencies are rejected through software (DSP lock-in) filtering.  Would it be possible to design a lock-in amplifier using ADAU170?




I was thinking to use ADAU1701 DSP chip, with SigmaStudio graphical development tool in order to design Lock-in amplifier as shown in the figure. I added noise, to the input signal of interest(500Hz), the reference signal is also 500 Hz, two multipliers have been used as mixers for IQ demodulation(after multiplication of signals, we should get DC(0Hz) signal and 1000Hz signal because its output will be two signals with f1-f2 and f1+f2 frequencies), Hilbert transform was used to the output signal and its 90 phase shifted version. After demodulation, it goes through the filter in order to filter out 2f frequency and etc.




I was thinking to buy EVAL-ADAU1701MINIZ, together with USBi control interface board. If there is a better alternative, I would be glad to know.




 




 





								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	










	

	

					



			








	
	
	
	



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                on Dec 2, 2021 12:22 PM
            
            
					
    
	
    

		
		
    
					
    Hello there. I am Beste. I'm a university student. Is there any other function that we can use to get phase in lock-in circuit other than hilbert transform? Also, apart from this circuit, can we draw a lock-in circuit using different elements?Thank you from now. Have a good day.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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                                 Analog Employees 
                                
                            
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                on Dec 4, 2021 4:18 PM
            
            
												
						in reply to bestekemaloglu
					
									
    
	
    

		
		
    
					
    Hi Beste,
    

    What hardware / software are you using in your lock-in circuit?
    

    It looks like the Hilbert was used above in SigmaStudio because the signal generator did not have quadrature outputs (sine / cosine.) If you are using SigmaStudio and the ADAU1701 specifically, you might ask in:
    

    https://ez.analog.com/dsp/sigmadsp/
    

    If you're looking for general information on lock-in techniques, do a web search on "lock-in detection", there are lots of application notes.
    

    This is an old thread, if you have any follow-on questions, please start a new one and refer back to this one if you want.
    

    -Mark
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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													0
							
			
				
									
							        
            
                                                                                                        
      
                            
    • 
                                 Analog Employees 
                                
                            
      • 
                        
     
                                                           			
			                            
                        
                on Dec 4, 2021 4:18 PM
            
            
												
						in reply to bestekemaloglu
					
									
    
	
    

		
		
    
					
    Hi Beste,
    

    What hardware / software are you using in your lock-in circuit?
    

    It looks like the Hilbert was used above in SigmaStudio because the signal generator did not have quadrature outputs (sine / cosine.) If you are using SigmaStudio and the ADAU1701 specifically, you might ask in:
    

    https://ez.analog.com/dsp/sigmadsp/
    

    If you're looking for general information on lock-in techniques, do a web search on "lock-in detection", there are lots of application notes.
    

    This is an old thread, if you have any follow-on questions, please start a new one and refer back to this one if you want.
    

    -Mark
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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