Question 3.SP.13: The circuit of Fig. 3-17 uses current- (or shunt-) feedback ......

Schaum’s Outline of Electronic Devices and Circuits [1089587]

The circuit of Fig. 3-17 uses current- (or shunt-) feedback bias. The Si transistor has $I_{CEO} ≈ 0, V_{CE\text{sat}} ≈ 0$ , and $h_{FE} = 100$ . If $R_C = 2 kΩ$ and $V_{CC} = 12 \text{V}$ , size $R_F$ for ideal maximum symmetrical swing (that is, location of the quiescent point such that $V_{CEQ} = V_{CC}/2$ ).

3.17

Step-by-Step

The 'Blue Check Mark' means that this solution was answered by an expert.
Learn more on how do we answer questions.

Application of KVL to the collector-emitter bias circuit gives
$(I_{BQ} + I_{CQ})R_C = V_{CC} – V_{CEQ}$

With $I_{CQ} = h_{FE}I_{BQ}$ , this leads to
$I_{BQ} = \frac{V_{CC} – V_{CEQ}}{(h_{FE} + 1)R_C} = \frac{12 – 6}{(100 + 1)(2 × 10^{3})} = 29.7 μ\text{A}$

Then, by KVL around the transistor terminals,
$R_F = \frac{V_{CEQ} – V_{BEQ}}{I_{BQ}} = \frac{6 – 0.7}{29.7 × 10^{-6}} = 178.5 kΩ$

Related Answered Questions

Question: 3.SP.15

Find the value of the emitter resistor RE that, when added to the Si transistor circuit of Fig. 3-17, would bias for operation about VCEQ = 5 V. Let ICEO = 0, β = 80, RF = 220 kΩ, RC = 2 kΩ, and VCC = 12 V. ...

Verified Answer:

Application of KVL around the transistor terminals...

Question: 3.SP.14

For the amplifier of Fig. 3-17, CC = 100 μF, RF = 180 kΩ, RL = 2 kΩ, RS = 100 kΩ, VCC = 12 V, and vS = 4 sin(20 × 10³πt) V. The transistor is described by the default npn model of Example 3.2. Use SPICE methods to (a) determine the quiescent values (IBQ, ICQ, VBEQ, VCEQ) and (b) plot the input and ...

Verified Answer:

(a) The netlist code that follows models the circu...

Question: 3.SP.12

Collector characteristics for the Ge transistor of Fig. 3-15 are given in Fig. 3-16. If VEE = 2 V, VCC = 12 V, and RC = 2 kΩ, size RE so that VCEQ = -6.4 V. ...

Verified Answer:

We construct, on Fig. 3-16, a dc load line having ...

Question: 3.SP.10

The Si transistor of Fig. 3-14 is biased for constant base current. If β = 80, VCEQ = 8 V, RC = 3 kΩ, and VCC = 15 V, find (a) ICQ and (b) the required value of RB. (c) Find RB if the transistor is a Ge device. ...

Verified Answer:

(a) By KVL around the collector-emitter circuit, [...

Question: 3.8

The signal source switch of Fig. 3-9(a) is closed, and the transistor base current becomes iB = IBQ + ib = 40 + 20 sin ωt μA The collector characteristics of the transistor are those displayed in Fig. 3-9(b). If VCC = 12 V and Rdc = 1 kΩ, graphically determine (a) ICQ and VCEQ, (b) ic and vce, and ...

Verified Answer:

(a) The dc load line has ordinate intercept [lat...

Question: 3.7

For the transistor circuit of Fig. 3-8(a), R1 = 1 kΩ, R2 = 20 kΩ, RC = 3 kΩ, RE = 10 Ω, and VCC = 15 V. If the transistor is the generic npn transistor of Example 3.3, use SPICE methods to determine the quiescent values IBQ, VBEQ, ICQ, and VCEQ. ...

Verified Answer:

The netlist code below models the circuit. EX3_...

Question: 3.SP.28

In the circuit of Fig. 3-8(a), RC = 300 Ω, RE = 200 Ω, R1 = 2 kΩ, R2 = 15 kΩ, VCC = 15 V, and β = 110 for the Si transistor. Assume that ICQ ≈ IEQ and VCEsat ≈ 0. Find the maximum symmetrical swing in collector current (a) if an ac base current is injected, and (b) if VCC is changed to 10 V but ...

Verified Answer:

(a) From (3.5) and (3.7),

I_{CQ} ≈ I_{EQ} ...

Question: 3.SP.27

In the circuit of Fig. 3-10(a), the transistor is a Si device, RE = 200 Ω, R2 = 10R1 = 10 kΩ, RL = RC = 2 kΩ, β = 100, and VCC = 15 V. Assume that CC and CE are very large, that VCEsat ≈ 0, and that iC = 0 at cutoff. Find (a) ICQ, (b) VCEQ, (c) the slope of the ac load line, (d) the slope of the dc ...

Verified Answer:

(a) Equations (3.5) and (3.7), give

I_{CQ...

Question: 3.SP.21

The Si Darlington transistor pair of Fig. 3-21 has negligible leakage current, and β1 = β2 = 60. Let R1 = R2 = 1 MΩ, RE = 500 Ω, and VCC = 12 V. Find (a) IEQ2, (b) VCEQ2, and (c) ICQ1. ...

Verified Answer:

(a) A Thévenin equivalent for the circuit to the...

Question: 3.SP.33

The amplifier of Fig. 3-27 uses an Si transistor for which VBEQ = 0.7 V. Assuming that the collector-emitter bias does not limit voltage excursion, classify the amplifier according to Table 3-4 if (a) VB = 1.0 V and vS = 0.25 cos ωt V, (b) VB = 1.0 V and vS = 0.5 cos ωt V, (c) VB = 0.5 V and vS = ...

Verified Answer:

As long as

v_S + V_B > 0.7 \text{V}[/la...