THS4601: About Necessary of bias canceling resistor about circuit likes fig26. on datasheet.

Morning, 

The idea of a bias current cancellation applies if both input have matched currents. JFET and CMOS input do not, so adding a resistor on the V+ input to gnd does nothing for DC precision in this circuit. Normally you would do that for a transimpedance design when using a bipolar input device like the OPA838. 

Also, The THS4601 is pretty old - you might look at the OPA810 

Hi Niinuma,

the THS4601 is a FET-OPAmp and shows only a very small input bias current of 100pA at room temperatur. So, there's actually no need for a cancellation resistor. But if you insist in adding such a cancellation resistor, don't forget to put a cap in parallel to this resistor.

What RF do you want to mount?

Kai

Dear kai.

Good day,

thanks your good advise and quickly response.

I am trying to make a simple luminometer.

I decided not to use resistor.

thank you.