- 12th April 2004, 09:36 #1

- Join Date
- Dec 2002
- Posts
- 52
- Helped
- 0 / 0
- Points
- 3,511
- Level
- 13

## op amp attenuator

Hi friends;

I have a question about using op amp as attenuator.

Can i use op amps for Gain<1.

Bests.

- 12th April 2004, 09:53 #2

- Join Date
- Apr 2004
- Posts
- 34
- Helped
- 0 / 0
- Points
- 1,676
- Level
- 9

## op amp gain less than 1

Yes ofcourse yous in inverting mode if the feed back resistor is less than the input resistor

Gain =-Rf/Ri

and you can add an other unity inver to get non-invering gain <1

- 12th April 2004, 09:53

- 12th April 2004, 10:30 #3

- Join Date
- Mar 2004
- Posts
- 15
- Helped
- 0 / 0
- Points
- 1,722
- Level
- 9

## opamp attenuator

Dear friend,

Yes ofcourse you can use the amplifier as a attenutor(gain<1) but be carefull about stability. What most of the people used to do is they check the stability of apmifier in unity gain mode, that would be the worst case of stability in most of the cases where the gain is more than one , This may not be true in this case.

- 12th April 2004, 10:30

- 12th April 2004, 10:48 #4

- Join Date
- Apr 2004
- Posts
- 34
- Helped
- 0 / 0
- Points
- 1,676
- Level
- 9

## op-amp attenuator

stabilty depends on frequency as will.

- 12th April 2004, 10:48

- 12th April 2004, 13:28 #5

- Join Date
- Dec 2002
- Posts
- 52
- Helped
- 0 / 0
- Points
- 3,511
- Level
- 13

## op amp gain < 1

Dear friends;

I was sure thar i can use the op amp as attenuator.

But i am intersting that khow what is the specs for using op amp as the attenuator (1/20) for 10MHZ input?

Can i use AD844 or simular Op amp for this reason?

I will be happy if you can help me.

Bests.

- 12th April 2004, 13:53 #6

- Join Date
- Apr 2004
- Posts
- 34
- Helped
- 0 / 0
- Points
- 1,676
- Level
- 9

## less than unity gain op amp

At 10 Mhz opamp as attenuater is not aggod choice. you should use an other technique. although AD844 might give you some gain also if you want at 10Mhz

- 12th April 2004, 16:20 #7

- Join Date
- Dec 2001
- Location
- China
- Posts
- 166
- Helped
- 3 / 3
- Points
- 2,788
- Level
- 12

## using an op amp as an attenuator

Can i use op amps for Gain<1.

of course:

it will perform to change impedance in some case.

- 12th April 2004, 16:24 #8

- Join Date
- Feb 2004
- Posts
- 36
- Helped
- 1 / 1
- Points
- 1,907
- Level
- 10

## attenuator using op amp

Why dont you use a simple divider network - the op amps are not so stable for gains lower then 1 !

- 12th April 2004, 18:51 #9

- Join Date
- Dec 2001
- Posts
- 99
- Helped
- 2 / 2
- Points
- 3,106
- Level
- 13

## op amp attenuators

Ignore the replies about stability issues with NI amplifiers having a gain less than one.

In this case the stability will be determined by the noise gain (from non-inverting input to output) which will approach 1 (from above) as the inverting gain is decreased towards zero.

- 12th April 2004, 20:48 #10

- Join Date
- Feb 2004
- Posts
- 36
- Helped
- 1 / 1
- Points
- 1,907
- Level
- 10

## non inverting op amp gain less than 1

OK I'll reply once why dont you use simple divider network followed by an OP AMP unity gain follower?

- 12th April 2004, 23:53 #11

- Join Date
- Dec 2001
- Posts
- 99
- Helped
- 2 / 2
- Points
- 3,106
- Level
- 13

## attenuator 18db opamp

Because in most cases there will be no advantage in doing so. Remember that it is usually preferable to operate operational amplifiers in an inverting mode since distortion due to common-mode gain is minimised.