Question

a) Using the constant voltage drop (CVD) model, what is the minimum input voltage that can reach the MOS circuitry before a diode turns on, shunting the current to ground? (At this point you can assume R1 = R2 = 0Ω)

b) Using the constant voltage drop (CVD) model, what is the maximum input voltage that can reach the MOS circuitry before a diode turns on, shunting the current to the supply (Vdd)? (At this point you can assume R1 = R2 = 0Ω)

c) Assume the input protection diodes are far enough from the supply and ground that a wire resistance of R1 = R2 = 1Ω is present. Using the CVD model, how much current would flow if one forces 5.5V at the input (Vin)?

d) What direction would the current from part c flow? (write down the correct answer)
i.    Towards the supply (Vdd)
ii.    Towards ground
iii.    Towards input voltage (Vin)
iv.    Towards the MOS Circuits

e) In part c, the CVD model was used. Given that each diode will carry 4A of current at 0.84V for strong forward bias and that the thermal voltage is 0.026V, use the full exponential equation for the diodes to determine how much current actually flows in part d. (Hint: Calculate the reverse leakage current first and then iterate the answer. Only 3 iterations are needed)

Diodes are frequently used to clamp input pins (Vin) of MOS integrated circuits to prevent excess voltage from reaching sensitive circuitry. For the input protection circuit shown in Figure 2, answer the following questions. Vdd -2.8V and they are Silicon Diodes R. Vin CIRCWITS Circui Noa Da 21 Figure 2