Homework Assignment #3

EE 477 Spring 2012 Professor Parker

Hardcopies due in the course boxes on the third floor of EEB 5 PM 2/14/12

Ecopies due 11:59 PM 2/14/12 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 = 2.5 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

You might want to wait to solve problems 6-8 until after the Thursday lecture.

1. (10 %) An NMOS transistor has Vds = 1.4v. Vs = .5 V. Is the transistor in the linear region of operation when Vgs =.9v.?

2. (10%) A PMOS transistor has Vg = .5 V , Vds = -2.5 V. Vd = 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 = 2.5v. Vout = 0v at time t = 0. The final output voltage at t = infinity is Vout = 0.9v. What was the gate voltage Vg, assuming that Vg remained steady the entire time?

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 = 0.7v. and Vout = 1.4 v. Vgn = 2v, and Vgp = 1.7 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 = 1.1v, Vs = 2.2v, and Vg = 1.2v. Assume the transistor width is 12 lambda and the length is 2.5 lambda.

6. (10%) Assume an inverter is on segment B of the input/output transfer curve. If V_in = 1.2 v, what is the minimum value of V_out to remain in the B segment?

7. (10%) Now assume that an inverter is on segment D of the input/output transfer curve. If Vin = 1.8 v, what is the maximum value of Vout to remain in the D segment?

8. (10%) Assume an inverter is on segment B of the input/output transfer curve. If V_in is known, and the widths/lengths of the two transistors are known, how would you compute V_out? Outline your method.

9. (10%) Two PMOS transistors are connected in series. Ernie Engineer tries to transfer a "0" from input to output. What is the output voltage at time = infinity?

10. (5%) What is the effective channel resistance of an NMOS transistor that has W=L?

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