EE477 - HW2

Homework Assignment #2 Corrected problem 2

EE 477 Fall 2018 Professor Parker

Hardcopies due in EE 477 box in EEB Basement 5 PM Sept. 14, 2018

OR Ecopies due 5 PM Sept. 14, 2018 using Assignment Dropbox on DEN

To ensure academic privacy, please use a cover page on your homework hard copies that does not contain any work.

Assume (unless stated otherwise in each problem):

V_dd = 1.8 v., V_ss = Gnd = 0 v.,

V_tn = .4 v., V_tp = -.4 v,

V_tn(body effect) =.55 v., V_tp(body effect) = -.55 v.

Leakage current per transistor = .2 namp.

ε₀ (epsilon) = 8.85 X 10 -14 F/cm and ε_oxide(epsilon) = 3.9

Rs of silicide = 4 Ω per □ (ohms per square). Rs of metal1 = .08 Ω per □ square (ohms per square). Rs of poly = 4.1 Ω per □ (ohms per square).

Rs of n diffusion =4.7 Ω per □ (ohms per square).

Rs of p diffusion =3.4 Ω per □ (ohms per square).

C_jbsn = 17.27 x 10^-4 pF/ μm²and C_jbswn = 4.17 x 10^-4 pF/ μm (micrometer).

C_jbsp = 18.8 x 10^-4 pF/ μm²and C_jbswp = 3.17 x 10^-4 pF/ μm (micrometer).

l (lambda) = .100 μ (microns), 100 nm.

β_n (beta)=k_n = 219.4 W/L μ A(microamps)/V²and β_p (beta)= k_p = 51 W/L μ A/V²

T_ox = 57 angstroms for thinox, and 5000 angstroms for thick oxide.

1) Consider the following circuit. At time t = 0, nodes Vx, Vy and Vout are completely charged (1.8 Volts).

1a) Show the source and drain of each transistor on the diagram just after t=0, when current starts flowing in some transistors. Are there some sources and drains that cannot be determined? Advance time a bit to predict better. 3 pts.

1b) What region is each transistor in at t = 0? 3 pts.

1c) Solve for Vx, Vy and Vout at t = ∞. Ignore body effect. 3 pts.

1d) What region is each transistor in at t = ∞? 3 pts.

Again assume initial conditions (Vx, Vy, Vout completely charged). Now take body effect into account.

1e) What happens to Vx, Vy and Vout at t = ∞?. 3 pts.

1f) What region is each transistor in at t = ∞? 3 pts.

2) The PMOS transistor below shown is in the linear region. Given: V_tN = 0.6V,

2a) Calculate Vgs and Vds and verify that the PMOS transistor is in the linear region. 3 pts.

2b) Find the current Idsp flowing through it. Be careful with units - International System of Units (SI) (you can find info in Wikipedia) and powers of 10. 3 pts.

2c) Ignoring the V_ds² term, draw the equivalent circuit of the transistor. What is the resistance value? 2 pts.

2d) If the source voltage is now decreased from 1.7 V, at what value does the current become 0? What is the region of operation when this happens? 2 pts.

3) In this transmission gate, Vout is initially 1.1 Volts.

3a) Show the sources and drains of the two transistors. 2 pts.

3b) What are the regions of operation of the NMOS and PMOS transistors as Vout changes over time? Show your calculations. 10 pts.

4) Current vs Voltage curves for a PMOS transistor are shown below.

4a) Why are there multiple blue curves?. 2 pts.

4b) What is region left of the red curve the red curve? 2 pts.

4c) Mark the blue curve where Vgs = 0.0v. 2 pts.

4d) Which axis is current and which is voltage? Are the values negative or positive?. 6 pts.

Old midterm questions:

1. (5%) Sketch an equivalent circuit for a PMOS transistor in saturation.

3 (10%) Sketch a stick diagram for a 5-input NAND gate, labeling all the layers. If you cannot use color use dashes -------- or dots ........... to indicate different layers.

5. a) (10%) Show a transistor-level design of a compound gate that implements the function

OUT = NOT [WX + YZ + P(QRS + VT + U)]. Do not change the Boolean equation or rearrange it.

b) (3%) Mark the sources and drains of all transistors on the circuit diagram.

c) (3%) Circle all transistors that are subject to the body effect. Show answer on the circuit diagram

7 (8 %) Ernie Engineer wants to asynchronously set the output of the first latch of a flip flop to 1, so that the final flip flop output is reset. Does the circuit below guarantee the latch output is set? Why or why not?

8. (9%) In the circuit shown below, V_in rises to Vdd at t = 0+ . What is V_out at t = infinity?