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Here are the solutions for and .
: Given the information appearing in Fig. 4.119, determine:
Given: VCC=12V, IB=40μA, VC=6V, β=80. The emitter is grounded, so VE=0V.
a) IC
Step 1: Use the relationship between collector current and base current.
IC=βIB
Step 2: Substitute the given values.
IC=80×(40×10−6A)
Step 3: Calculate IC.
IC=3200×10−6A=3.2mA
The collector current is 3.2mA.
b) RC
Step 1: Calculate the voltage drop across RC.
VRC=VCC−VC
VRC=12V−6V=6V
Step 2: Use Ohm's Law to find RC.
RC=ICVRC
Step 3: Substitute the values.
RC=3.2×10−3A6V
Step 4: Calculate RC.
RC=1875Ω=1.875kΩ
The collector resistor is 1.875kΩ.
c) RB
Step 1: Assume VBE=0.7V for a silicon transistor. Since VE=0V, VB=VBE.
VB=0.7V
Step 2: Calculate the voltage drop across RB.
VRB=VCC−VB
VRB=12V−0.7V=11.3V
Step 3: Use Ohm's Law to find RB.
RB=IBVRB
Step 4: Substitute the values.
RB=40×10−6A11.3V
Step 5: Calculate RB.
RB=282500Ω=282.5kΩ
The base resistor is 282.5kΩ.
d) VCE
Step 1: Use the definition of VCE.
VCE=VC−VE
Step 2: Substitute the given values.
VCE=6V−0V
Step 3: Calculate VCE.
VCE=6V
The collector-emitter voltage is 6V.
: Given the information appearing in Fig. 4.120, determine:
Given: IB=20μA, RC=2.2kΩ, VCE=7.2V, IE=4mA. The emitter is grounded, so VE=0V.
a) IC
Step 1: Use the relationship between emitter, collector, and base currents.
IE=IC+IB
Step 2: Rearrange to solve for IC.
IC=IE−IB
Step 3: Substitute the given values.
IC=(4×10−3A)−(20×10−6A)
IC=0.004A−0.00002A
Step 4: Calculate IC.
IC=0.00398A=3.98mA
The collector current is 3.98mA.
b) VCC
Step 1: Calculate the collector voltage VC. Since VE=0V.
VC=VCE+VE
VC=7.2V+0V=7.2V
Step 2: Calculate VCC using the voltage drop across RC.
VCC=VC+ICRC
Step 3: Substitute the values.
VCC=7.2V+(3.98×10−3A)×(2.2×103Ω)
VCC=7.2V+8.756V
Step 4: Calculate VCC.
VCC=15.956V
The supply voltage is 15.956V.
c) β
Step 1: Use the definition of β.
β=IBIC
Step