written 3.9 years ago by |
Performing DC analysis by open circuiting all capacitors
The voltage across resistor R2 can be given by the expression
The current through R1 is
I1=VCC−VBR1
Similarly, current through R2 is
I2=VB−VEER2
Since there is no path for these currents to take another loop, these currents have got to be the same which brings us to the foll. equation
VCC−VBR1=VB−VEER2
VCC−VBR1−VB−VEER2=0
VCCR2−VBR2−VBR1+VEER1R1R2=0
VCCR2−VBR2−VBR1+VEER1=0
VCCR2+VEER1=VB(R1+R2)
∴VB=VCCR2+VEER1R1+R2
NOTE: Using the above equation, we can easily get VB but just in case you want a easier equation, we will simplify the obtained equation
VB=VCCR2+VEER2−VEER2+VEER1R1+R2
VB=VEE(R1+R2)R1+R2+R2(VCC−VEE)R1+R2
∴VB=VEE+(VCC−VEE)×R2R1+R2
∴VB=−5+(5−(−5))×2×10312×103+2×103
∴VB=−3.571 V
RB=R1||R2
RB=12×103×2×10312×103+2×103
∴RB=1.714 KΩ
Applying KVL to Base - Emitter Loop
VB−IBRB−VBE−IERE+VEE=0
But, IE=(1+β)IB
VB−IBRB−VBE−(1+β)IBRE+VEE=0
VB−VBE+VEE=IB[RB+(1+β)RE]
IB=VB−VBE+VEERB+(1+β)RE
IB=−3.571−0.7+61.71×103+(1+100)500
IB=33.135 μA
We know that, IC=βIB
IC=100×34.237×10−6
∴IC=3.135 mA__
Applying KVL to the Collector - Emitter Loop
VCC−ICRC−VCE−IERE+VEE=0
But IC≈IE
∴VCC−IC[RC+RE]−VCE+VEE=0
VCE=VCC−IC[RC+RE]+VEE
∴VCE=5−3.135×10−3[5×103+500]+5
∴VCE=−8.288 V__