Math Problem Statement

Calculate Vo and VCE in the transistor circuit assuming that the transistor is in the forward active mode with VBE = 0.7V and β = 100.

Solution

Let's solve for VOV_O and VCEV_{CE} in this transistor circuit.

Given Data:

  1. VBE=0.7VV_{BE} = 0.7 \, \text{V}
  2. β=100\beta = 100
  3. RB=10kΩR_B = 10 \, \text{k}\Omega
  4. RC=500ΩR_C = 500 \, \Omega
  5. RE=200ΩR_E = 200 \, \Omega
  6. Supply voltages:
    • VCC=12VV_{CC} = 12 \, \text{V} (for the collector side)
    • VBB=5VV_{BB} = 5 \, \text{V} (for the base side)

Step-by-Step Solution:

1. Calculate Base Current IBI_B:

Using Kirchhoff's Voltage Law (KVL) for the base circuit: VBB=IBRB+VBE+IEREV_{BB} = I_B R_B + V_{BE} + I_E R_E Since IE=(1+β)IBI_E = (1 + \beta) I_B, we substitute IEI_E and rearrange to find IBI_B: 5=IB(10×103)+0.7+IB(1+100)(200)5 = I_B (10 \times 10^3) + 0.7 + I_B (1 + 100)(200) 5=IB(10,000+20,200)5 = I_B (10,000 + 20,200) IB=50.730,200=4.330,2001.424μAI_B = \frac{5 - 0.7}{30,200} = \frac{4.3}{30,200} \approx 1.424 \, \mu A

2. Calculate Collector Current ICI_C:

Using IC=βIBI_C = \beta I_B: IC=100×1.424μA0.1424mAI_C = 100 \times 1.424 \, \mu A \approx 0.1424 \, \text{mA}

3. Calculate VOV_O:

Using Ohm's law on the collector resistor RCR_C: VO=VCCICRCV_O = V_{CC} - I_C R_C VO=12(0.1424×500)V_O = 12 - (0.1424 \times 500) VO=120.0712=2.876VV_O = 12 - 0.0712 = 2.876 \, \text{V}

4. Calculate VCEV_{CE}:

The voltage VCEV_{CE} is given by: VCE=VOVEV_{CE} = V_O - V_E Since VE=IEREV_E = I_E R_E and IEICI_E \approx I_C (assuming β\beta is large): VE=0.1424×200=2.848VV_E = 0.1424 \times 200 = 2.848 \, \text{V} VCE=2.8760.7=2.005VV_{CE} = 2.876 - 0.7 = 2.005 \, \text{V}

Answers:

  1. VO=2.876VV_O = 2.876 \, \text{V}
  2. VCE=2.005VV_{CE} = 2.005 \, \text{V}

Would you like further details, or do you have questions?

Related Questions:

  1. How would changing β\beta affect VOV_O and VCEV_{CE}?
  2. What happens to VOV_O if RER_E is increased?
  3. How would the circuit behave if VBEV_{BE} was different?
  4. How can we determine if the transistor is in saturation?
  5. What is the role of RCR_C in setting the output voltage?

Tip:

To verify if a transistor is in the active region, check if VCE>VBEV_{CE} > V_{BE}.

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Math Problem Analysis

Mathematical Concepts

Circuit Analysis
Transistor Biasing
Ohm's Law
Kirchhoff's Voltage Law

Formulas

KVL: VBB = IB RB + VBE + IE RE
IC = β IB
VO = VCC - IC RC
VCE = VO - VE
VE = IE RE

Theorems

Kirchhoff's Voltage Law (KVL)
Ohm's Law

Suitable Grade Level

Undergraduate (Electronics/Electrical Engineering)