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Refer to Figure 9 rO=r_{O}=\infty Assume VBE=0.7 V\left|V_{B E}\right|=0.7 \mathrm{~V}
(A) For 9.10.1

Question 3

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Refer to Figure 9.10.1 below.
 Refer to Figure 9.10.1 below.       Figure 9.10.1 Note: Neglect the Early effect; that is, assume  r_{O}=\infty . Assume  \left|V_{B E}\right|=0.7 \mathrm{~V} . (a) For  V_{A}=V_{B}=0 \mathrm{~V}  and neglecting all base currents, design the circuit of Fig. 9.10.1 so that each of  Q_{1}  and  Q_{2}  operates at a dc bias current of  0.25 \mathrm{~mA}, V_{C}=V_{D}=+10 \mathrm{~V}, V_{E}=0 \mathrm{~V} , and  Q_{5}  operates at a dc bias current of  3 \mathrm{~mA} . Specify the dc bias current at which each of  Q_{3}  and  Q_{4}  will be operating and give the required value of  R_{1}, R_{2} ,  R_{3}, R_{4} , and  R_{5} . (b) If  \beta=99 , what must the value of each of the two resistances labeled  R_{e}  be so as to obtain an input differential resistance of  40 \mathrm{k} \Omega  ? (c) Find the differential voltage gain of the input stage,  Q_{1}-Q_{2} . (d) Find the voltage gain of the second stage,  Q_{3}-Q_{4} . (e) Find the voltage gain of the output stage,  Q_{5} . (f) Find the overall voltage gain,  v_{e} /\left(v_{b}-v_{a}\right) .

Figure 9.10.1
Note: Neglect the Early effect; that is, assume rO=r_{O}=\infty . Assume VBE=0.7 V\left|V_{B E}\right|=0.7 \mathrm{~V} .
(a) For VA=VB=0 VV_{A}=V_{B}=0 \mathrm{~V} and neglecting all base currents, design the circuit of Fig. 9.10.1 so that each of Q1Q_{1} and Q2Q_{2} operates at a dc bias current of 0.25 mA,VC=VD=+10 V,VE=0 V0.25 \mathrm{~mA}, V_{C}=V_{D}=+10 \mathrm{~V}, V_{E}=0 \mathrm{~V} , and Q5Q_{5} operates at a dc bias current of 3 mA3 \mathrm{~mA} . Specify the dc bias current at which each of Q3Q_{3} and Q4Q_{4} will be operating and give the required value of R1,R2R_{1}, R_{2} , R3,R4R_{3}, R_{4} , and R5R_{5} .
(b) If β=99\beta=99 , what must the value of each of the two resistances labeled ReR_{e} be so as to obtain an input differential resistance of 40kΩ40 \mathrm{k} \Omega ?
(c) Find the differential voltage gain of the input stage, Q1Q2Q_{1}-Q_{2} .
(d) Find the voltage gain of the second stage, Q3Q4Q_{3}-Q_{4} .
(e) Find the voltage gain of the output stage, Q5Q_{5} .
(f) Find the overall voltage gain, ve/(vbva)v_{e} /\left(v_{b}-v_{a}\right) .

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