Homework Assignment #3

EE 477 Fall 2012 Professor Parker

Hardcopies due in the course boxes on the third floor of EEB 5 PM 10/01/12

Ecopies due 11:59 PM 10/01/12 using the "Assignment" Function on DEN

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

Assume for the problems below that V_dd = 1.8 v, V_tp0 is -.7 v. and V_tn0 is .7 V. V_tpbodyeffect is -.9 v. and V_tnbodyeffect is .9 V.

Assume ß_n (k_n)= 219.4 W/L µ A(microamps)/V² and ß_p (k_p)= 51 W/L µ A/V²

Work problems 3-6 after the lecture on Wed.

1. (10 %) An NMOS transistor has Vds = 1.4v. Vs = .2 V. Is the transistor in the linear region of operation when Vgs =1.4v.?

2. (10%) A PMOS transistor has Vgs = -1 V , Vd = .5 V. Vg = 0 v. What region of operation is it in?

3. a) (5 %) An NMOS transistor is used as a pass transistor. The input voltage is Vin = 2v. The gate voltage Vg=1.8v. The voltage Vout = 0.1v at time t = 0. What is the final output voltage at t = infinity?

b) (5%) Does body effect occur when the transistor transfers 0's from input to output?

4. a) (7 %) Identify the sources and drains in a transmission gate at t=0+ when Vin = 0.8v. and Vout = 1.3 v. Vgn = 1.7v, and Vgp = 0 v.

b) (8 %) What regions are the two transistors in when t approaches infinity? Be sure to justify your answers.

5. (10%) Compute the drain current flow IDS in a PMOS transistor when Vd = .9v, Vs = 2.2v, and Vg = .5v. Assume the transistor width is 10 lambda and the length is 2 lambda.

6. (5%) What is the effective channel resistance of an NMOS transistor that has W=2L?

7. (10%) Explain what can happen if the minimum length/width for poly is violated.

8. (5%) Where do parasitic bipolar transistors occur?

9. (5%) If all the MOS transistors in a layout are off, can latchup occur?

10. (10%) Explain why in an N-Well process we need to have an n-tap.

11. (10%) a) Suppose that an engineer has designed the following layout for an inverter. Identify the three errors in the layout.

b) What material is the green color in the PMOS transistor?