Can I use analog switch as chopper switches

Hi John,

I am looking into this and I will get back to you ASAP.

Regards,

David

Hi John,

I do not see any fundamental reason why the ADG could not be used to build this discrete chopper amplifier.

I am curious why you need to do this discretely? Have you looked over our Zero-Drift amplifier portfolio?

Zero-Drift Amplifiers | Analog Devices 

Regards,

David

Hi, David:

    Thanks for the reply!

     After I did more study, I understand now that I can not use ADG1436 and ADG1419 due to their large charge injection, instead I can use ADG733. The reason I am not using zero drift amplifier is that the noise level I need to below 0.8nV/sqrt(Hz) for frequency > 0.1Hz. The best auto zero amplifier will be around 15nV.

Hi John,

I'm glad you found a solution. Just to note for ultra low charge injection you could also look at our ADG1208 family. The ADG1236 and ADG1219 are SPDT switches.

Regards,

David

David:

   I can not use ADG1208 family, even their charge injection is very small compared with ADG733. because their resistance is too high 120 Ohm which gives 1.4nV/sqrt(Hz) for one side and about 2nV/sqrt(Hz) for noise summation of both sides while it need to below 0.5nV/sqrt(Hz). In addition, the larger resistance, the larger serial voltage which will be developed from imbalanced charge current. ADG733 has 2.5 Ohm while only 3PC charge injection , so it is the best candidate.