Download EECS 40, Midterm 2, Spring 2000: Circuits, Transients, Op-Amps, Semiconductors and more Exams Microelectronic Circuits in PDF only on Docsity!
EECS 40, Spring 2000
Midterm 2
Professor King
Problem #1: Circuits with Dependent Sources [20 points]
a) Find V 0. [4 pts]
b) In the circuit below, the independent source values and resistances are known. Use the nodal analysis technique to write 3 equations sufficient to solve for Va, Vb, and Vc. To receive credit, you must write your answer in the box below. [6 pts]
DO NOT SOLVE THE EQUATIONS!
Write the nodal equations here:
c) Consider the following circuit:
EECS 40, Spring 2000 Midterm 2 Professor King 1
i) Find the voltage Vab. [5 pts]
ii) What is the current ia when the terminals a and b are shorted together? [3pts]
iii) Draw the Thevenin Equivalent Circuit. [2pts]
Problem #2: Transient Response [30 pts]
a) In the circuit below, the switch has been in the closed position for a long time.
i) Find the value of vR just after the switch opens (t = 0+). [3 pts]
ii) How much energy is dissipated in the 1 k-ohm resistor after the switch is opened? [2 pts]
b) In the circuit below, the 5 micro-farad capacitor is initially charged to 5 V (vC1(0-) = 5 V). The switch is then closed at time t = 0. What is the final value of vC1? [5 pts]
c) The following is a circuit model for an NMOS inverter, in which the transistor is turned on at time t = 0:
Problem #1: Circuits with Dependent Sources [20 points] 2
Find Vout in terms of V1, V2, R1, R2, R3, F4. [10 pts]
(Hint: The superposition method might be helpful here.)
Problem 4: Semiconductor properties; p-n diodes [25 pts]
a) Consider a silicon sample maintained at 300K under equilibrium conditions, uniformly doped with 1x10^16 cm-3^ phosphorus atoms. The surface region of the sample is additionally doped uniformly with 5x10^16 cm-3^ boron atoms, to a depth of 1 micron, as shown in the figure below.
i) In the figure above, indicate the type of the regions (I and II) by labelling them as "n" or "p" type. [ pts]
ii) What are the electron and hole concentrations in Region I? [5 pts]
n = _______________ cm-
p = _______________ cm-
Problem #3: Op-Amp Circuits [25 pts] 4
iii) What is the sheet resistance of Region I? [5 pts]
iv) Suppose any voltage between 0 V and 5 V can be applied to Region I. What fixed voltage ("bias") would you apply to Region II, to guarantee that no current would ever flow between Region I and Region II? Briefly explain your answer. [3 pts]
b) If a diode is operated only within a small range of forward-bias voltages, its behavior can be accurately modelled by a resistor, whose value is dependent on the bias voltage. Device an expression for the diode "small-signal" resistance:
in terms of the saturation current Is, the bias voltage V, and the absolute temperature T. [5 pts]
Rdiode = ________________________
c) Plot vL vs. VIN for -10 V < VIN < 10 V on the axes provided, for the circuit below, Note that the diode is a perfect rectifier. Label the axes. [5 pts]
Posted by HKN (Electrical Engineering and Computer Science Honor Society)
University of California at Berkeley
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Problem 4: Semiconductor properties; p-n diodes [25 pts] 5
