Attenuation for LT1128

Hi hong_96:  You could do that, but why not just use a resistive attenuator, such as 1k into 1 Ohm, or 10k into 10 Ohms?

If you need an inversion, you could take some attenuation, and then invert with a medium noise opamp, and then take the final attenuation resistively?

Here's the thing: when you attenuate using inverting opamp, the signal gain may be -0.1, but the "noise gain" is 1.1.

Hi hong_96:  You could do that, but why not just use a resistive attenuator, such as 1k into 1 Ohm, or 10k into 10 Ohms?

If you need an inversion, you could take some attenuation, and then invert with a medium noise opamp, and then take the final attenuation resistively?

Here's the thing: when you attenuate using inverting opamp, the signal gain may be -0.1, but the "noise gain" is 1.1.

Hi, thanks for the reply.

The reason I am trying to avoid using resistive attenuator because I heard that there will be issues with power loss, thermal drift and also noise (if I use high value resistors).

While doing my own research, I found out that noise gain is usually associated with the stability of the op amp. I was wondering if "noise gain" increases the overall noise in the circuit or is it just used as a way to determine stability.

Also, I read that any unity gain stable op-amp can be used as an attenuator (source: ez.analog.com/.../amplifier-attenuator-or-both). My question is, is there any limit to the amount of attenuation I can get (for eg, -20db,-60db,-100db) before the op amp becomes unstable?

Appreciate your advice! Thanks!