AD8603 Noise simulation

Question

Hello, 
 The LTSpice noise simulation of AD8603 gives around twice the noise density @ 1 kHz. It should be 22 nV/sqrt(Hz) flat and start the 1/f then below 1 kHz. See sim below connected as follower. Thanks. 
 
 From data sheet: 
 
 Marcelo

PaulCA · Accepted Answer

Hello, Yes. I am using LTSpice XVII. I'm sorry, I forgot that I have to download AD8603's model from analog.com since I couldn't find the part on the component's Library. I have autogenerated a symbol from the .cir file (netlist) that I have downloaded from here AD8603 Datasheet and Product Info | Analog Devices that's why I have a different symbol. I have already fixed this on my end and created a symbol using the .cir file. I have also simulated your circuit on my end and here is the result: From my simulation, I am also getting about 27 nV/sqrt(Hz) @ a frequency of 1 kHz. I'm thinking that the model that you are using is not updated. Can you try downloading the part's model from here: AD8603 Datasheet and Product Info | Analog Devices under Tools and Simulations 
 After downloading, open the .cir file using LTSpice and autogenerate a symbol from the netlist. After generating the symbol, it should look like this: By viewing the Pin table, we can see the Pin Names and their corresponding SpiceOrders. (For SpiceOrder 1 -> non-inverting input, SpiceOrder 2 -> inverting input, etc.) Click save, then close. After that, use this model on your circuit by navigating through Components. Let me know if the result of your simulation changes. Thank you 
 Best Regards, Paul)

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AD8603 Noise simulation

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