High Input impedance OPamp

Takumi Suzuki1

Mastermind 8480 points

Other Parts Discussed in Thread: OPA391, OPA328, OPA928, OPA325, LMP7701, OPA333, OPA320, OPA392

Hi,

I would like to ask you to tell me CMOS or JFET OPamps which have very high input impedance.

I would like to know the OPamps which have the impedance around over 1Tohm with low voltage and RRIO, if possible.

Thank you for your support.

Best Regards,

Takumi

8 months ago

+1 Marek Lis 8 months ago

TI__Guru 62290 points

Both, CMOS and JFET input op amp may have input impedance in the range of 1Tohm but for the low voltage and RRIO CMOS would be the only choice. Please take a look at OPA328, OPA392, OPA391, OPA320, OPA325, OPA333 for 5V supply or LMP7701 (Vs up to 12V) and OPA928 (Vs up to 36V), etc.

0 Takumi Suzuki1 8 months ago in reply to Marek Lis

Mastermind 8480 points

Marek-san,

Thank you for your support !

Let me study these OPamps you showed me.

Sorry, one more question please.

What device name is the CMOS OPamp?

I suppose that type "OPA3xx" and "OPA9xx" seems to be CMOS type.

Is my idea correct?

Or is there any other device name about CMOS or J-FET?

Thanks in advance.

Regards,

Takumi

+1 Marek Lis 8 months ago in reply to Takumi Suzuki1

TI__Guru 62290 points

There are three basic type of transistors that might be used to implement input stage of any op amp circuit: one of the two field effect transistor type: CMOS (MOSFET) and JFET (junction field effect transistor) or BJT (bipolar junction transistor). For more info, please click on the following link:

https://www.electronicshub.org/transistors-classification-and-types/

All op amps on the list above are CMOS - this is typical for RRIO op amps.

0 Takumi Suzuki1 8 months ago in reply to Marek Lis

Mastermind 8480 points

Marek-san

Thank you for your kind support !

Regards,

Takumi

+1 Marek Lis 8 months ago in reply to Takumi Suzuki1

TI__Guru 62290 points

Glad to help. Good luck with your project!

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High Input impedance OPamp