Inverting Summing Amplifier

An inverting amplifier can be constructed as a summing amplifier. The output voltage is a weighted sum of the inverting input signals V1, V2, ……, Vn. Note that each summing coefficient may be independently adjusted by adjusting the corresponding “feed-in” resistor (R1 to Rn). Figure below is an application of inverting configuration and the Vout to Vin transfer function.


An inverting summing amplifier below has three inputs using 100kΩ resistors and a feedback resistor of 50kΩ.
What is VOUT in terms of V1 and V2? If V1 = 2V and V2 = 2V, V3 = 3V what is VOUT ?


VOUT = -50 (V1/100 + V2/100 + V3/100)

VOUT = -50 ((2V+ 2V + 3V )/100 = -3.50V

© 2017 Microchip Technology, Inc.
Information contained on this site regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.