8/7/2019 Elektronie Giri 1.Vize 8 Mart 2004-Ali Zeki-www.teknikhayat.com

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Introduction to ElectronicsMid-Term Exam #1

Ali Zeki (105 minutes) March, 8th, 2004

Important parameters of the devices used in Figure 1 are as follows:

Resistors : RX=1.5k, RY=3.3k For all diodes (D1,D2,D3,D4) :

IS=5.10-15A , Pd,max=75mW

For the Zener diodes D3 and D4 :VZk=4.7V , IZmin=0.3mA , rz=7

VT=25.9mV [T=300K]NOTE: Use rz only in small signal analysis. Figure 1

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a) By making use of the constant voltage drop model (with VD0=0.6V) for theforward-biased diodes, determine the range for vI along which D3 operates

securely in Zener region (Name the limits of the range as VI,min and VI,max). [20p]

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b) By using the accurate model iD

=IS

(evD/VT -1)for the diodes (except for the

Zener region), determine the currents iXand iY for each of the input voltage

values below:

i)vI=3V , ii)vI=9V , iii)vI=-3V , iv)vI=-9V [40p]

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c) If the input voltage vI is as shown inFigure 2, use small signal approximation

and the corresponding DC diode currents

found in (b) to draw the waveforms ofthe currents iX and iY. [40p]

Note for (c):If you couldnt obtain the requiredDC diode currents in (b), then you can still obtain

them by using the constant voltage drop model,

BUTyou will get less points from (c) !.

Figure 2

GOOD LUCK