Consider the op-amp circuit at right, which contains a diode for which we can as

Question

Consider the op-amp circuit at right, which contains a diode for which we can assume the relationship between current and voltage is I=I0eaV. This is the same type of device that is used as a solar cell in the solar cell lab. Compute vo as a function of vs, Rs, Io, and a in this circuit. Assume ideal op-amp behavior. Suppose you are given 4 ideal op amps, 3 diodes for which I=I0eaV, and an unlimited number of resistors (of any value you choose). Assume I0=1x 10-7A and a=40. Design a circuit that takes two input voltages, V1 and v2, and generates an output vo=0.01v1/v2.

Explanation / Answer

as shown in the circuit :

vn = vp = 0

so V = vn - vo = - vo ...(1)

nodal equation at node vn gives :

(vs - 0)/Rs = I

=> Vs/Rs = Io eaV = Io e-(avo)

hence

  e-(avo) = Vs / ( Io Rs)

take ln for both sides :

=> -a vo = ln [Vs/( Io Rs)]

=> vo = -(1/a) ln [Vs/( Io Rs)]

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.