A. Parker EE 477L Spring 2010
Homework Assignment #4
due 3/2/10 either in the boxes in EEB at 5 PM or
online using the DEN assignments function at 11:59 PM
Assume for the problems below that Vdd = 2.5 v, Vtp0 is -.7 v. and Vtn0 is .7 V. Vtpbodyeffect is -.9 v. and Vtnbodyeffect is .9 V.
Assume ßn (kn)= 219.4 W/L µ A(microamps)/V2 and ßp (kp)= 51 W/L µ A/V2
1. a) (12 %) A PMOS transistor is used as a pass transistor. Vout=2.5v at t=0+. What is the final output voltage when Vin = 0.0v? What region of operation is the pass transistor in at t=0+? at t=infinity?
b) (5 %) Does body effect occur when the transistor transfers 0's from input to output?
2. a) (10 %) Identify the sources and drains in a transmission gate at t=0+ when Vin = 2.5 v. and Vout = 0.0 v. Let Vgn = 2.0 v, and Vgp = 0.0 v.
b) (15 %) What regions are the two transistors in when t=0+? when t= infinity? Be sure to justify your answers.
3. (8 %) When a positive gate voltage is applied to an NMOS transistor, and a depletion region is formed, is there a net charge in the depletion region? If so, is it positive or negative?
4. (10%) Compute the drain current flow IDS in an NMOS transistor when VDS = 0.7 v, and VGS = 1.7 v. Vs= 0.2 v Assume the transistor width is 8 lambda and the length is 5 lambda.
5. (10%) Compute the channel resistance of a PMOS transistor when Vgs = - 2.0 v and the transistor is in the linear region of operation. Vs= 2.0 v. W = 6 lambda and L = 3 lambda.
6. (10 %) An NMOS transistor is in the transition between the linear and saturation regions of operation. VS = 0.25 V. Is the transistor is in the linear region of operation when VGS = 2.25 v., what is the value of VDS?
7. (10%) Assume an inverter is on segment D of the input/output transfer curve. If ßn= ßp, what is the minimum value of Vin that would allow the inverter to remain in the D segment?
8. (10 %) If an inverter is on segment B of the input/output transfer curve, Vout = 2.4v and Vin = .8v, prove that the NMOS transistor is in saturation.