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Unformatted text preview: EE105, Midterm 1, Fall 1995 EE105 Fall, 1995
Midterm 1
B.E. Boser Device Parameters: (use in all problems)
NMOS
PMOS
threshold voltage 0.7V
0.7V
gate oxide
2fF/um^2
2fF/um^2
mobility
400 cm^2/Vs 150 cm^2 / Vs
Problem #1
Doped Silicon (20 points)
A sample of Boron doped Silicon is 1 cm long and has crosssection with A=2mm^2
Paramaters: u sub n = 400 cm^2/Vs, u sub p = 150 cm^2 / Vs
(a) [5 points] Is the sample ntype or ptype?
(b) [5 points] If a 5V battery is connected across the Silicon sample, a current of 3mA flows. What is
the majority carrier (doping) concentration of the sample? (c) [5 points] With the voltage source removed, what are the electron and hole concentration in the
Silicon sample at room temperature?
(d) [5 points] What concentration of Arsenic doping is needed to get a current of 100mA when the
experiment described in part (b) is repeated?
Problem #2
Inverter with PMOS current source load (30 points) file:///C/Documents%20and%20Settings/Jason%20Raft...0%20Fall%201995%20%20Boser%20%20Midterm%201.htm (1 of 4)1/27/2007 4:43:33 PM EE105, Midterm 1, Fall 1995 You are a supervisor at SmartLogic Inc. One of your engineers has invented the "new" inverter shown
below and proposes to use it in your next project (note that the gate of the PMOS is tied to the ground,
rather than the input of the inverter). You are suspicious and first analyze its performance ...
Parameters: V sub DD = 5V, W sub M1 = 4um, W sub M2 = 2um, L sub M2 = 1um (a) [5 points] On the graph below, sketch carefully, I2 vs V2. Mark the regions of operation (i.e. off,
triode, or saturation) and compute the transition points accurately (indicate voltage and current values
in graph). (b) [5 points] On the graph below, sketch carefully, I1 vs Vout for M1 and I2 vs Vout for M2. In the
saturation region, the plot should be accurate. Use Vin = 0, 1,2,2.5,3,3.5V. Indicate transition points
between different regions of operation in the graph. file:///C/Documents%20and%20Settings/Jason%20Raft...0%20Fall%201995%20%20Boser%20%20Midterm%201.htm (2 of 4)1/27/2007 4:43:33 PM EE105, Midterm 1, Fall 1995 (c) [5 points] Using your results from (b), construct graphically the voltage transfer characteristics of
the inverter, Vout vs Vin on the graph below. Calculate VOH and VOL (d) [5 points] Calculate the threshold of the inverter.
(e) [5 points] What is the static power dissipation of this inverter when the input voltage Vin is 0V or
5V, respectively?
(f) [5 points] Find the average power dissipation of this inverter driving CL = 100fF at fclk = 100
MHz. Ignore "switching power", but include static power dissipation, if any.
Problem #3
NOR gate (25 points)
Paramaters: all device sizes (NMOS and PMOS) L = 1um, W = 5um, VsubDD = 5V
file:///C/Documents%20and%20Settings/Jason%20Raft...0%20Fall%201995%20%20Boser%20%20Midterm%201.htm (3 of 4)1/27/2007 4:43:33 PM EE105, Midterm 1, Fall 1995 (a) [5 points] Draw the transistor level circuit diagram of a static 3input NOR gate. Label the inputs,
A, B, and C, the output Y, and the supplies, DsubDD and GND.
(b) [5 points] What is the threshold voltage VM of the gate?
(c) [5 points] Find the input capacitance Cgate for each input.
(d) [5 points] Assuming that the gate drives a load CL = 200fF, find the worstcase delays tPLH and tPHL.
Problem #4
Pass transistor logic (25 points)
Parameter: VDD = 3V (a) [7 points] Write the truth table for the gate shown above with inputs A, B, and C, and output Y
(b) [2 points] What logic function does the gate realize?
(c) [4 points] Draw the minimum complexity transistor level implementation for the same logic
function using static CMOS gates. What is the minimum number of transistors needed?
(d) [6 points] Find the width Wn and Wp of the NMOS and PMOS transistors of a CMOS transfer
gate with Ron = 5kOhms for Vin = VDD. Assume Ln = Lp = 1um and ignore body effect. Beware:
VDD = 3V
(e) [6 points] Assuming Ron = 5kOhm, find the worstcase propagation delay tp when input A is
switching. Posted by HKN (Electrical Engineering and Computer Science Honor Society)
University of California at Berkeley
If you have any questions about these online exams
please contact mailto:examfile@hkn.eecs.berkeley.edu file:///C/Documents%20and%20Settings/Jason%20Raft...0%20Fall%201995%20%20Boser%20%20Midterm%201.htm (4 of 4)1/27/2007 4:43:33 PM ...
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This note was uploaded on 05/17/2009 for the course EE 105 taught by Professor Kingliu during the Spring '07 term at University of California, Berkeley.
 Spring '07
 KingLiu
 Electrical Engineering

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