Design a negative summing amplifier to add three input voltages with the following requirements: (i) The output voltage of this circuit must be equal to 2 times the negative sum of the inputs. (ii) Only an operational amplifier and suitable passive components to be used. (iii) Use a variable power supply of 20V. The design should show the steps involved in deriving the suitable component values and show the schematic diagram with all parts marked with their respective values. (12 marks) Recall the concept of a differential amplifier and design a suitable circuit with OP-AMP to produce the output Vo given by: Vo = (VS1 + VS2) - (VS3 + VS4) where VSI, VS2, VS3 and Vs4 are the input voltages. The design should include any assumptions made, choice of components selected and sho the final schematic diagram with all parts marked with suitable values.