EE 3220 Test 1

EE 3220 Test 1 - EE3220: Test 1 - 3/24/05 Name [120»...

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Unformatted text preview: EE3220: Test 1 - 3/24/05 Name [120» dag/“1'94 1 Directions: This test contains 4 problems. You have 50 minutes to complete this test. Do not spend excessive time on any one problem. Partial credit will be given for partial knowledge. Provide answers in indicated spaces where applicable. Do not write in the table below. Graphing or storage calculators are not permitted. 2 — — 3 3 — _ loo [0 \A c] 6;: EE3220: Test 1 — 3/24/05 1. For the following BJT inverter: Name (a) Create a complete small signal model. Do not neglect r0. (5 pts) (b) Derive the small signal gain from your model. (10 pts) (c) What are the small signal input and output impedances? (5 pts) 10V «Val =7, /25)/.w71)( 77f-67 I’M /00/ I00 I’ab/ = 97‘ u.— ‘ 2 m m r /: ((2510:) 7* 5," = fan I; ~ C 3'» m «at, .EE3220: Test 1 - 3/24/05 Name 3 2. Derive the small signal gain of the CMOS inverter. Assume both devices operate in the constant current region. Do not neglect output impedances or the body effect. (20 pts) VDD Q1 k "‘ V°”‘ {fed- 1 oz ¢ ‘ m) l. . EE3220: Test 1 - 3/24/05 Name 4 3. Answer the following questions about the MOSFET differential amplifier in order. Do not neglect the body effect. Transistors Q1 and Q2 are identical. (a) What is the small signal impedance presented to Q1 by the source of Q3? Verify your answer with a model. (10 pts) (b) Assuming all transistors Operate in the constant current region and v1 = —v2 why is the node connected to the sources of Q1 and Q2 a virtual ground for small differential signals? (5 pts) ’ (c) Prove the small signal differential gain of the circuit from 12m to vout where um = 121 —- 122 is. equal to —.5\/¥3 for very large output resistances and no body effect. Assume v1 and 122 are equal in magnitude. (15 pts) Figure 3: MOSFET Amplifier EE3220: Test 1 — 3/24/05 ' Name 5 Extra Space J) 19} 7/2, 5, .L Q) MW 5: egu/ 151 Mfg/NZ»)? and ‘f/WII/C "4 323'”- Ivr'l/‘jcmv/ca’c ejhcl tad oil/ankle chiff/WLJ. a/Jlb/r’m/ (hf/(40465:) 2/501 [ill ,zt ll (Miran/- {Viv x'A/P I). , fl: War/V: (If: 1:; 4%” )0“, 5) a, Iii/01f CmCoL/ /" e w EE3220: Test 1 - 3/24/05 ~ Name 6 4. Answer the questions below in order concerning the differential amplifier pictured: (a) Choose RE such that the current in the resistor is .93mA (5 pts) (b) What are the resulting DC voltages at the collectors of the transistors? (5 pts) (c) What is the small signal differential gain to the collector of Q1 where um = 111 4112? Neglect the output resistance. (5 pts) (d)' What is the common mode gain to the collector of Q1? (5 pts) (e) Redesign the circuit using a current mirror to improve the common mode gain by at least a factor of 10. Use identical transistors and verify the new gain. (10 pts) 10V l3=100 vA=2oo n=1.6 Figure 4: BJT Amplifier a .3 ) .2, 2 v 71.4, ,e: /JA’ 4) M- ruff/a: c £35 &) I‘ll/m 2 ’Zmfla = .1 'yayfléflf)" 2 o2(fl£),?fa d9 ’40.:— gg: -'5- _ In \L To . e) _ ,6, g Mk )7”? G ‘fifw :J/fié/Msr—gfi‘) 42:0.” w 94 __.= -r!./ . 73'" 267/526 .EE3220: Test 1 - 3/24/05 Eztm Space Name ...
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This test prep was uploaded on 04/20/2008 for the course EE 3220 taught by Professor Audiffred during the Spring '06 term at LSU.

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EE 3220 Test 1 - EE3220: Test 1 - 3/24/05 Name [120»...

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