Unity Gain op amp circuit?

jetbat · 3rd May 2009, 03:16 AM

Hi, I was wondering if this op amp is running at unity gain? I know with just the two 22k resistors it is. But with 3, I don't know. Anyone have some insight?

Thanks
Scott

kaos · 3rd May 2009, 03:50 AM

It’s an inverting summing amp with two inputs (it basically adds the two signals together and inverts). For inputs of +1V & +1V you get –2V at the output. For inputs of +1V,-1V you get 0V at the output, +1V & 0V = -1V, and so forth.

AndrewT · 3rd May 2009, 04:00 PM

Yes, it's a unity gain opamp.

The gain at each input is set by the feedback resistor divided by the input resistor.
In both the inputs, the gain is 22/22 = 1

As Kaos has said, the opamp ADDs all the input signals. You can put on as many as you like

jetbat · 5th May 2009, 12:29 AM

Thanks, I understand now.

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3rd May 2009, 03:50 AM	#2
kaos diyAudio Member Join Date: Dec 2005 Location: Los Angeles	It’s an inverting summing amp with two inputs (it basically adds the two signals together and inverts). For inputs of +1V & +1V you get –2V at the output. For inputs of +1V,-1V you get 0V at the output, +1V & 0V = -1V, and so forth.

3rd May 2009, 04:00 PM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Yes, it's a unity gain opamp. The gain at each input is set by the feedback resistor divided by the input resistor. In both the inputs, the gain is 22/22 = 1 As Kaos has said, the opamp ADDs all the input signals. You can put on as many as you like

5th May 2009, 12:29 AM	#4
jetbat diyAudio Member Join Date: Nov 2008 Location: Maryland	Thanks, I understand now.