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**Unformatted text preview: **Physics 3330 Midterm - Fall 2009 Name: , L U T 5 October 22, 2009
Version 2 of 2 Student #: 100 points total
Lab Instructor: I have neither given -xor received help on this exam. Signed: Problem 1 _. __________: For the following vol'age divider, what output voltage Vout do you measure if: 5 Vin=1V ——-v Vout 10 M9 (1a) (4 points) if your measurement device is ideal? V * IOHJL 13M 1 V
= W'— = __.
5“ IonLH’nn. 3 1' (1b) (6 points) if you measure with your DMM from lab? (The DMM has an input impedance of IOMQ) .m « m4
i i 114.! (On IL- ra; trier, Van—f ( i~ ’(J‘O//&/
f ‘ J... .L 1,
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l ,‘, Problem 2 . (2) (9 points) Which of the following properties below are properties of an ideal op—amp?
Circle all that apply. a infinite voltae 1:»
b) unity voltage gain c) zero input impelance d) infinite input impedance
e) zero output impedance f) infinite output impedance Problem 3 . (3) (6 points) The vaiues of Rin and RF are chosen to obtain a low frequency gain of
1000. The circuit is built using the LF3 56 op-amp from lab (unity gain frequency of
5MHz). What is the approximate 3dB corner frequency? Problem 4 . . (4) Use the following. circuit diagram to answer the questions below. Assume the op—
amp golden rules app! y exactly, and neither the output voltage nor output current are saturated. If = 1—; +1;
———-——9- R Vb Vout (4a) (2 points) What is the voltage at the inverting input? V: OVag/vg — 95.
(4b) (6 points) Assume Vb=0V and Va is not equal to zero. What is Vout in terms of
the iven uantities?
g q 1+ *ﬂ/ A 7 giﬂV‘=V.%z
W e. CQ/fc-v aw: Io “3'4 24:34.. C;’<k;/_°’(‘¢’~,f_ k‘°-_
- Vq -OV_ V a‘°‘*+ heﬁfff’o/
IQ -—' K :: 72$- ;°;&¢€/¢de —' ; "/71 I'd. waif-L;
1; = m-v— ___ yovwvzd «wk-4-,
It )1
$13—51 I; Veal—57%
V0k+=—Irk -= %‘+;—(/Q (4c) (3 points) Assume Va=OV and Vb is not equal to zero. What is Vout in terms of
the given quantities? 57 Kym“- f/y/ V044,)" = - V6 (4d) (6 points) Assume neither Vb nor Va are zero. What is Vout in terms of the given
quantities? - . . + M
I [1" 5755:.“ I! lld-ez/ [.5 37"! f‘tsfous-gy 3’0 .M'Wb‘,/C“¢ £3 fl‘n//y 44“ (“IV/affrg‘a1 d’ﬂ “2" flu-0
a [I = via“: farm/7‘5:- (4e) (3 points) Wha: math operation does the transfer function of this circuit
accomplish? Circle xiie correct answer.) (a) Adds the voltages a and Vb toget e (b) Subtracts the voltages Va and Vb from each other (c) Multiplies the voltages Va and Vb together
(d) Divides the voltages Va and Vb by each other Problem 5 (5) (6 points) Based on the following plot for the transfer function of a bandpass filter,
what is the quality factor Q? Marking your work on the plot might help provide
partial credit. A gr?d is provided so that you can be precise. I» 1.0 0.9 0.8 Transfer Function lVout/Vin l
O 95 100 105 110 115 120
Frequency [kHZ] Problem 6 . A 1 Vpp, 10 kHz square wave (see graph below) is applied to the input of a low pass
ﬁlter. The low pass filter has a 3dB corner frequency of 10 kHz. (6a) (4 points) What is the characteristic (i .e. l/e) rise and fall time? Give a numerical
value for this characzeristic time. =—-—-——— .— JT- ——L-———"- :-
1, “13005 '— 1W3,“ Zﬂ’C/GYHL) Ig7ﬂs (6b) (6 points) Draw the waveform for Vout versus time on the provided graph. Vin is
provided on the graph. Be sure to clearly label the value of Vout one characteristic time
after the transition of the input square wave from 0 to 1V and from IV to 0V. A grid is provided so that you can be precise. 0 25 SO 75 100 125 150 175 200 Problem 7 . (7) Answer the questions below for the following circuit. Assume that 10V >Vin > 3V. +15V C‘
Vin Vout (7a) (3 points) Label the base, emitter and collector on the diagram above. (7b) (4 points) Write Vout in terms of Vin. (7c) (4 points) What is the collector current in terms of Vin and R?
:9 6159.4...» 1. A ——a 06 n”"/l¢€t‘!¢/¥\ I : _. ;— ’ .
Irma->12 ﬂag) i‘é'g’W) (7d) (3 points) Is the base current larger or smaller in magnitude than the collector
current? 1; =73 :3
,6”: loo fa 3’00
"I" ﬁrez/S Problem 8 (8) Use the following circuit diagram to answer the questions below. Assume the op—
amp golden rules apply exactly, and neither the output voltage nor output current are
saturated. Note that it is possible to solve most of 8b and 8c without knowing the results for 8a. Vin
Vout (Sa) (9 points) Provide both (1) a complex expression for the transfer function
Vout/V in and (2) an expression for the absolute value of the transfer function
lVout/Vinl. Your expression should depend on R“, CF, RF and angular frequency (1). (8b) (6 points) If Rin : le, RF: 10kg, what value of CF produces a 3dB corner
frequency in the transfer function at f = co/Zrc =10kHz‘? 74005 = UM" : .J—w
2”” Z’P’ZF CF E)CF : —-l——————- :__,_/..( l ' ___/_'
2V4.“ ’ZF 277’ /0"#:.)[/o"/L> CF: /’6'(0_?F ‘1 LénF (8c) (10 points) Using the component values from 8b, draw a Bode Plot for the circuit
on the log-log plot below. Include a large enough range of frequencies to show the low
and high frequency behavior of the circuit. Label all axis and important values on the
graph. If you are stuck on the previous sections, consider what the gain ought to
look like at very low frequencies and at very high frequencies and see if you can
smoothly connect the two regimes. ’00 Eiiiiiiiiﬁ iiiiiiiﬁiiiiiiiiaﬁiiiiiiiﬁﬁiiiiliiﬁiiiiiiﬂ
low fr? 1 ﬂ ------- I- ------- n—n ------- n— uuuuuu :-
9°34. 0
642/0 .—7 <9 1334,, = msz
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