Homework Assignment #5

Prof. Parker Due Feb. 23, 2007 at 4:30 PM in EEB 348. Solutions will be posted at 8 PM EE 477 Spring 2007

Assume V_dd = 2.5 v. for these problems. Assume V_tp is -.7 V. Assume V_tn is .7 V. Tox = 57 angstroms for thinox, and 5000 angstroms for thick oxide. ε0 (epsilon) = 8.85 X 10 -14 F/cm and εoxide(epsilon) = 3.9 lambda = .18 microns. Cjbsn = 17.27 x 10-4 pF/ μm2 and Cjbswn = 4.17 x 10-4 pF/ μm (micrometer). Cjbsp = 18.8 x 10-4 pF/ μm2and Cjbswp = 3.17 x 10-4 pF/ μm (micrometer).

1. (10%) For the inverter discussed in class along with the input output transfer curves, assume both PMOS and NMOS devices are in saturation. If |ß_n/ ßp| = 4, , what is Vin? Use the equation from the text.

2. (10%) A PMOS transistor has V_GS = -0.9 V. If the transistor is in the linear region of operation, what are the possible values of V_DS?

3. (10%) An NMOS transistor in an inverter has V_GS = 1.1 V. |ß_n/ ßp| = 0.5. What region of operation is it in?

4 (10%) For the circuit shown in the homework 2 solution to problem 2a, which transistor(s) would be subject to the body effect?

5. (15%) A transmission gate is in the following state: V_in = 2.4 v. V_out = .6 v. At time t=0, the control input turns both transistors on instantaneously. What region of operation is the NMOS transistor in at t=0⁺? As t approaches infinity?

6. (10%) In an inverter, at what voltage does a PMOS transistor change from cutoff to saturation?

7. (15%) Compute the gate capacitance of an NMOS transistor that has dimensions 3 times minimum size.

8. (20%) Compute the diffusion capacitance of the drain of a PMOS transistor that has dimensions 5 lambda by 4 lambda. Use the method described in the lecture.