Homework Assignment #4
EE 477 Fall 2014 Professor Parker
Hardcopies due in the course boxes in the basement of EEB 5 PM 10/6/14
OR Ecopies due 5 PM 10/6/14 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. Turn in EITHER a hard copy or ecopy, not both.
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 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) (10 %) Identify the sources and drains in a transmission gate at t=0+ when Vin = .3 v and Vout = 1.4 v. Let Vgn = 2.5 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.
2. a) (10 %) Assume that an inverter is on segment A of the input/output transfer curve. What is the range of input voltages that will prevent the inverter to move into segment B after reaching steady state?
b) (2%) is there current flow between the vdd and gnd path of the inverter while the inverter is on segment A?
3. a) (5%) Assume for an inverter kn > kp. Would the input/output voltage transfer curve stays longer on segment A? If not, briefly explain what happens to the input/output voltage transfer curve.
b) (3%) Assume that for the condition kn > kp, the inverter is on segment D of the input/output voltage transfer curve. What is the maximum value of input voltage that keeps the inverter in segment D?
4. (5%) Assume kp=kn, what is the maximum output voltage to stay on region D? What would be the region of operation of the transistors if we exceed that voltage?
5. (7%) Asssume that kn = kp, initially Vin=Vdd and so the PMOS transistor of the inverter is in cutoff region. What are the regions of operation of the transistors in the inverter when Vin decreases to 1.7 V?
6. (5%) If the segment C of the input/output voltage transfer curve moves to the right, what is the effect on noise margins? Is high noise margin or low noise margin affected?
7. (3%) If the C segment occurs when Vin is lower than Vdd/2, what does that tell us about the ratio of kn and kp ?
8. (10%) What are the regions of operation of the transistors in the inverter when there is a current spike?
9. (10%) An inverter has the transistors sized so that the ratio of kp to kn = .5. Does this ratio imply that the transistor switches from high to low with a larger or smaller input voltage? What regions are the transistors in when Vin = Vdd/2?
10. a) (4%) Redraw the input/output voltage transfer curve of the inverter with the same details provided in solution of HW4 Fall 2012 asst4soln.pdf . Identify VIHmin, VILmax VOHmin, and VOLmax (in the text they use VIH, VIL VOH, and VOL) in the input/output voltage transfer curve of the inverter. Identify both points where slope of input/output transfer curve = -1
b) (2%) Define VIH, VIL VOH, and VOL and write down the definitions of HIGH noise margin and LOW noise margin.
c) (4%) To have an optimal inverter with high noise immunity, our goal would be to design an inverter such that VIH is very far from VIL or very close to VIL? Briefly explain your answer.
11. (5%) A novel inverter has the input/output voltage transfer curve like the one in the figure below. What are the values of VIL, VIH, VOL and VOH that give best noise margins? What are the HIGH and LOW noise margins?
