EE311-2009-THE9 - o = considering the following small...

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EE 311 Analog Electronics Take Home Exam Part VIII Due: December 23, 2009 (In class) 1) Consider the low-frequency response of the following DC coupled amplifier, implemented with an npn BJT and an enhancement mode n-type MOSFET (you can ignore r o for the M N transistor, but do not ignore r o for the Q NPN transistor). K n =200 A/V 2 K n = C ox ·μ n ·W/L V Tn = 3V = 0 V -1 I DC =1mA C gs =7.5 pF C gd =2.5 pF =50 V A =100V V BE = 0.7V C =2 pF f T =1.59 GHz V CC =5V R S = 0.5K R D = 1K R B = 86K R L = 20K C L =10 pF C 1 =10μF C 2 =5μF (a) Draw the low frequency small signal model of the amplifier. (b) Find (determine directly or derive) the small-signal voltage gain G (s) = V o (s)/V sig (s) in terms of circuit components and small signal parameters of the transistors. (c) Determine the midband gain G MB , and the low frequency poles p1 & p2 . (Note that the emitter and the collector capacitor does not interact since r
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Unformatted text preview: o = ) considering the following small signal parameters. (d) Estimate the low frequency 3-dB cut-off point, L , i) using the dominant pole approximation, if applicable. ii) using the approximate formula i i Zi Pi L 2 2 2 : iii) using the Short-Circuit Time Constant method. Considering the results in (i), (ii), and (iii), provide the best approximate value for wL. (e) Draw the high frequency small signal model of the amplifier and determine all of the circuit parameters. (f) Estimate the high frequency 3-dB cut-off point, H , using Open-Circuit Time Constant method (note here that you cannot directly determine the time constant due to Cgs, rather you should replace Cgs with a voltage source and determine the current it provides)....
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This note was uploaded on 05/25/2011 for the course EE 311 taught by Professor Murataskar during the Spring '11 term at Middle East Technical University.

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