# Can Inverting Op-Amps have positive gain?

Thread Starter

#### Alex Mechatronics

Joined Feb 24, 2020
4
I encountered a problem where it was asking to build two amplifiers. One of them must be inverting and the other one must be non-inverting amplifier. The problem was also telling that both of the amplifiers must have a gain of 5. I can manage to design the non-inverting amplifier to have a gain of 5. However I am a bit confused whether the problem asks me to build an inverting amplifier having a gain of 5 or -5? Please help I also attach the problem

#### ericgibbs

Joined Jan 29, 2010
18,655
hi Alex.
Welcome to AAC.
Do you know the equations for the Gain of Inverting and Non Inverting OPA's.???
E

Thread Starter

#### Alex Mechatronics

Joined Feb 24, 2020
4
Yes I know them. For inverting amplifier: Vout/Vin=Gain=-Rf/Rin and for non-inverting amplifier:Vout/Vin=Gain=1+R2/R1. However, If I have an inverting amplifier, the input voltage polarities will change for the output with a gain for a simple inverting amplifier. The question says the amplifier gain should be 5. Is it 5 or -5 ?

Thread Starter

#### Alex Mechatronics

Joined Feb 24, 2020
4
hi Alex.
Welcome to AAC.
Do you know the equations for the Gain of Inverting and Non Inverting OPA's.???
E
Hi by the way

#### crutschow

Joined Mar 14, 2008
34,047
The magnitude of the inverting gain is 5, but for the equation it's -5 (meaning it's inverting).

Thread Starter

#### Alex Mechatronics

Joined Feb 24, 2020
4
The magnitude of the inverting gain is 5, but for the equation it's -5 (meaning it's inverting).
Thank you so much for your help! Love this platform!

#### ericgibbs

Joined Jan 29, 2010
18,655
hi A,
So knowing that NI OPA equation, post what you think the amplifier circuit will be.
E

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