Resistor values for inverting amplifier?

[riie]

Hi all,

Is there any range of resistor values that should be used for an inverting op amp amplifier (Op27g)?
A gain of -100 is required.

Any reason why 20ohm and 2kohm combination doesn't work?
Voltage output is seen to be saturated.

Thanks!

 

[godfreyl]

Any reason why 20ohm and 2kohm combination doesn't work?

The input impedance of the amplifier will be 20 Ohms, which is probably too low. What's it for?

 

[riie]

It is to amplifiy a voltage signal and be read by a daq.

Which combination should I use instead?
1) 2k / 200k
2) 3.3k / 330k
3) 4.7k / 470k

 

[FvM]

2k feedback resistor is somewhat low, but may be suitable in some cases. The OP should be able to drive 2k at almost full swing.

Output saturated suggests input overload or wrong bias.

You usually want to measure all circuit voltages and analyze what's going wrong.