RB VBE 0.7 V Rc Vc Vcc lc = Bla lc = le VcclcRc- laRa - VBE = 0 Vccle Rc (le/B) Ra - VBE = 0 - Vcc - VBE = le Rc + (le/B)Ra Vcc VBE = le((Ra/B) + Rc) le= Vcc - Vee RB/B + Rc R₁ = ß [V Vcc - VBE le le = Bla . Rc (KVL) (IE CFB-bias) (RB CFB-bias)

Introductory Circuit Analysis (13th Edition)
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ISBN:9780133923605
Author:Robert L. Boylestad
Publisher:Robert L. Boylestad
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Solve IB and IE
U▬▬▬▬▬
Beta
100
150
200
250
300
RB
[mm]+">
VBE =
0.7 V
Rc
Vc
Collector-feedback bias.
Vcc = VBB
25
20
15
10
Vcc
RB = B
Rc
1k
1.2k
900
750
500
E =
B = 100
c =
lc = Bla
lc = le
Vcc - IcRc- laRB - VBE = 0
Vcc le Rc (le/B)RB - VBE = 0
Vcc VBE = le Rc + (le/B) Ra
Vcc
VBE IE((RB/3) + Rc).
| =
Vcc = 10V
B = 300
R₂ = ß
Vcc - Vee
Rc] = 100 [-
le
Vc = Vcc -lc Rc = 10-(1mA)-(4.7k) = 5.3V
Vcc - VBE
RB/B + Rc
Vcc - Vac
RA/B + R
Vcc= 10V
Vcc - Ver
lE
5
Example Calculations:
Find the required collector feedback bias resistor for an emitter current of 1 mA, a 4.7K collector
load resistor, and a transistor with B=100. Find the collector voltage VC. It should be
approximately midway between VCC and ground.
B = 100
Vcc - Vee
Rn/B+ Rc
RB
=
500
300
450
250
lc = le = 1MA
10 -0.7
1mA
le = Bla
The closest standard value to the 460k collector feedback bias resistor is 470k. Find the
emitter current IE with the 470K resistor. Recalculate the emitter current for a transistor with
B=100 and B=300.
Rc=4.7k
10 -0.7
470k/100 +4.7k
- Rc
10 -0.7
470k/300 +4.7k
B
(KVL)
Rg = 470k
(IE CFB-bias)
Rc = 4.7k
4.7k = 460k
7K] =
= 0.989mA
(RB CFB-bias)
= 1.48mA
lE
We see that as beta changes from 100 to 300, the emitter current increases from 0.989mA to
1.48mA. This is an improvement over the previous base-bias circuit which had an increase from
1.02mA to 3.07mA. Collector feedback bias is twice as stable as base-bias with respect to beta
variation.
Transcribed Image Text:U▬▬▬▬▬ Beta 100 150 200 250 300 RB [mm]+"> VBE = 0.7 V Rc Vc Collector-feedback bias. Vcc = VBB 25 20 15 10 Vcc RB = B Rc 1k 1.2k 900 750 500 E = B = 100 c = lc = Bla lc = le Vcc - IcRc- laRB - VBE = 0 Vcc le Rc (le/B)RB - VBE = 0 Vcc VBE = le Rc + (le/B) Ra Vcc VBE IE((RB/3) + Rc). | = Vcc = 10V B = 300 R₂ = ß Vcc - Vee Rc] = 100 [- le Vc = Vcc -lc Rc = 10-(1mA)-(4.7k) = 5.3V Vcc - VBE RB/B + Rc Vcc - Vac RA/B + R Vcc= 10V Vcc - Ver lE 5 Example Calculations: Find the required collector feedback bias resistor for an emitter current of 1 mA, a 4.7K collector load resistor, and a transistor with B=100. Find the collector voltage VC. It should be approximately midway between VCC and ground. B = 100 Vcc - Vee Rn/B+ Rc RB = 500 300 450 250 lc = le = 1MA 10 -0.7 1mA le = Bla The closest standard value to the 460k collector feedback bias resistor is 470k. Find the emitter current IE with the 470K resistor. Recalculate the emitter current for a transistor with B=100 and B=300. Rc=4.7k 10 -0.7 470k/100 +4.7k - Rc 10 -0.7 470k/300 +4.7k B (KVL) Rg = 470k (IE CFB-bias) Rc = 4.7k 4.7k = 460k 7K] = = 0.989mA (RB CFB-bias) = 1.48mA lE We see that as beta changes from 100 to 300, the emitter current increases from 0.989mA to 1.48mA. This is an improvement over the previous base-bias circuit which had an increase from 1.02mA to 3.07mA. Collector feedback bias is twice as stable as base-bias with respect to beta variation.
Expert Solution
Step 1

Given-

For a BJT circuit values are given as-

Beta VCC RC RB
100 25 1k 1k
150 20 1.2k 500
200 15 900 300
250 10 750 450
300 5 500 250

Base emitter voltage = 0.7 V

Emitter current, IE=VCC-VBERBβ+RC and IE=βIB

To find-

Base current and emitter current =??

steps

Step by step

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