A circuit has input voltages V1 and V2. Design the circuit so that Vo becomes

Vo = 10 INT(V1 dt) - 5V2. The input resistance of both voltage sources should be at least 100k(ohms). Assume ideal op-amp.

I have no idea where to start in this problem. Any hints?

 

Well, the first part of the equation is an integration function, thus you have to build an integrator circuit. The second part is a non-inverting amplifier with a gain of 5. Then you have to connect these two circuits to the inputs of a differential amplifier, with the integrator output connected on the non-inverting input and the non-inverting amplifier on the inverting input of the differential amplifier, to take the final expression on the output of the differential amplifier.

 

Isn't the second part an inverting amplifier, since there's a minus?

 

No, the minus will come later from the differential amplifier.

 

Can I also design an adder?

 

Yes, that's a better solution because you wont need an inverting amplifier on the output of the integrator with a gain of 1 to make the inverting output of the integrator non-inverting and obtain the positive sine on the equation.

 

Is it correct to say that R is the input resistances for both the integrator and the differentiator here?

http://www.allaboutcircuits.com/vol_3/chpt_8/11.html

 

Is it correct to say that R is the input resistances for both the integrator and the differentiator here?

http://www.allaboutcircuits.com/vol_3/chpt_8/11.html

For the integrator yes but not for the differentiator.

 

OK, so then I've tried. Here's my circuit (in paint, lol):

http://www.badongo.com/pic/4644958

(the capacitor is supposed to be 5 micro Farads, not 50)

 

That looks fine.

 

According to the solutions manual, what I should do is to couple an integrator and an inverting summing amplifier (adder).