ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9...

7
ECE3110 Homework #9 Fall 2011 1 1. Label the circuits below as Class A, Class B, or Class AB.

Transcript of ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9...

Page 1: ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9 Fall 2011 2 2. For Vsig=Vin=1+6sin( ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased

ECE3110 Homework #9 Fall 2011

1

1. Label the circuits below as Class A, Class B, or Class AB.

Page 2: ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9 Fall 2011 2 2. For Vsig=Vin=1+6sin( ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased

ECE3110 Homework #9 Fall 2011

2

2. For Vsig=Vin=1+6sin(ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased for correct operation. Assume

(1b) is biased at = 1. Sketch the output waveforms for all the circuits in Problem 1.

3. Calculate the efficiency for circuit 1b. Use = 1 and =10kΩ, VDD=VSS=5V.

=

= 14

= 14 4.8

110 4.85 = 11.5%

This is assuming a symmetric output and symmetric power supplies of equal value.

Page 3: ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9 Fall 2011 2 2. For Vsig=Vin=1+6sin( ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased

ECE3110 Homework #9 Fall 2011

3

The output is not symmetric in this case. One way of getting the average is to take the rms value.

= ∗ = !"

=#$ − #&'

√2 *

!"=

4.8 − 0.2√2

*

10 = 1.06,

Only one power supply of +5V:

- = ∗ = 1 ∗ 5 = 5

= -

= 1.065 = 21.2%

4. The datasheet of a bipolar transistor contains the following information:

Maximum allowable junction temperature TJmax = 100°C

Maximum power dissipation PDmax = 2 W at case temperature TC = 45°C

Junction-to-case thermal resistance θJC = 60 °C/W

Junction-to-ambient thermal resistance θJA = 100 °C/W

(a) What is the maximum case temperature to ensure safe operation at 0.2W?

(b) What is the case temperature when the transistor dissipates 500mW and the room is at 25oC.

Page 4: ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9 Fall 2011 2 2. For Vsig=Vin=1+6sin( ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased

ECE3110 Homework

For Problems 5-8. The above design uses

µpCox=60µA/V2, |VA|=40V. Neglect the effect of V

5. Fill in the empty spaces in the table above if A1=10V/V and the overall gain is A=200V/V.

6. (a) If C2=0.2pF, find the frequency of the second pole,

(b) Find the value of CC that results in

(c) Find the phase margin. Is the system stable

./*

.0 = 1 2#*3

PM=90 − tan89 :;:<=

− tan89 1:;:>

? where

PM=90 − tan89 1 @AAB9C9*B? − tan89 1@AA

C9D

Q (W/L) µCox (µA/V2) I(mA)

Q1 20 60 480E

Q2 20 60 480E

Q3 11 180 480E

Q4 11 180 480E

Q5 40 60 960E

Q6 10 180 960E

Q7 40 60 960E

Q8 40 60 960E

Homework #9 Fall 2011

4

The above design uses ±5V power supplies. Let |Vt|=0.5V, µnCox=180

|=40V. Neglect the effect of VA on the bias currents. Use the following table:

Fill in the empty spaces in the table above if A1=10V/V and the overall gain is A=200V/V.

ind the frequency of the second pole, fp2.

that results in ft =300MHz.

Find the phase margin. Is the system stable?

* = F*2GH*

= 1.92G0.2I = 1,512KLM

1 #N3O

? H = 12#N*3:;

? = 9#*3@AAB = .53IQ

? where .R = 1 2B=*3O

? = 1 9.S#*3A.C@/? = 571KLM

1@AABC9DB? = 90 − 11 − 30 = 49 (STABLE!)

Vov(V) VGS(V) gm(mA/V) ro(kΩ)

0.9 1.4 1 83.3

0.9 1.4 1 83.3

0.7 1.5 1.4 83.3

0.7 1.5 1.4 83.3

0.9 1.4 2.2 41.7

1.03 1.5 1.9 41.7

0.9 1.4 2.2 41.7

0.9 1.4 2.2 41.7

=180µA/V2,

on the bias currents. Use the following table:

Fill in the empty spaces in the table above if A1=10V/V and the overall gain is A=200V/V.

IQ

Page 5: ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9 Fall 2011 2 2. For Vsig=Vin=1+6sin( ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased

ECE3110 Homework

The above design uses ±1.5V power supplies. Let

µpCox=60µA/V2, |VA|=15V. Neglect the effect of V

7. (a) Find the input common mode range and the range allowed for

(b) Fill in the empty spaces in the table above.

Homework #9 Fall 2011

5

1.5V power supplies. Let IREF=300µA, |Vt|=0.7V, µnCox=180

|=15V. Neglect the effect of VA on the bias currents. Use the following table:

Find the input common mode range and the range allowed for vo.

Fill in the empty spaces in the table above.

=180µA/V2,

on the bias currents. Use the following table:

Page 6: ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9 Fall 2011 2 2. For Vsig=Vin=1+6sin( ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased

ECE3110 Homework #9 Fall 2011

6

8. Find the overall gain of the op amp. Find A1, A2, and the dc open loop voltage gain.

Page 7: ECE3110 Homework #9 Fall 2011ece3110/ECE3110F11_HW9sol.pdf · 2011. 12. 5. · ECE3110 Homework #9 Fall 2011 2 2. For Vsig=Vin=1+6sin( ωt)V and VDD=VSS=5V. Assume V1 (1a) is biased

ECE3110 Homework #9 Fall 2011

7

9. What is the overall voltage gain if a load resistor is placed on the output, RL=2k.

10. (a) If C2=1pF, find the frequency of the second pole, fp2.

(b) Find the value of CC that results in ft =200MHz.

(c) Find the phase margin. Is this system stable? If not, how can it be made stable?