# Question 4.SP.20: Fixed bias can also be utilized for the enhancement-mode MOS......

Fixed bias can also be utilized for the enhancement-mode MOSFET, as is illustrated by the circuit of Fig. 4-25. The MOSFET is described by the drain characteristic of Fig. 4-9. Let $R_1 = 60 kΩ, R_2 = 40 kΩ, R_D = 3 kΩ, R_L = 1 kΩ, V_{DD} = 15 \text {V, and} C_C → ∞$.   (a) Find $V_{GSQ}$.   (b) Graphically determine $V_{DSQ}$ and $I_{DQ}$.

Step-by-Step
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(a)  Assume $i_G = 0$. Then, by (4.3),
$R_G = \frac{R_1R_2}{R_1 + R_2} \quad \text{and} \quad V_{GG} = \frac{R_1}{R_1 + R_2} V_{DD}$            (4.3)

$V_{G S Q} = V_{G G} = \frac{R_2}{R_2 + R_1} V_{D D} = \frac{40 \times 10^3}{40 \times 10^3 + 60 \times 10^3} 15 = 6 \text{V}$

(b)  The dc load line is constructed on Fig. 4-9 with $v_{DS}$ intercept $V_{DD} = 15 \text{V}$ and $i_D$ intercept $V_{DD}/R_L = 5 \text{mA}$.   The Q-point quantities can be read directly from projections back to the $i_D$ and $v_{DS}$ axes; they are $V_{D S Q} \approx 11.3 \text{V}$ and $I_{D Q} \approx 1.4 \text{mA}$.

Question: 4.SP.19

## Identical JFETs characterized by iG = 0,  IDSS = 10 mA, and Vp0 = 4 V are connected as shown in Fig. 4-24. Let R_D = 1 kΩ, RS = 2 kΩ, and VDD = 15 V, and find (a) VGSQ1, (b) IDQ2, (c) VGSQ2, (d) VDSQ1, and (e) VDSQ2. ...

(a)   With negligible gate current, (4.2) gives [l...
Question: 4.SP.18

## For the series-connected identical JFETs of Fig. 4-23, IDSS = 8 mA and Vp0 = 4 V. If VDD = 15 V, RD = 5 kΩ, RS = 2 kΩ, and RG = 1 MΩ, find (a) VDSQ1, (b) IDQ1, (c) VGSQ1, (d) VGSQ2, and (e) VDSQ2. ...

(a) By KVL, V_{GSQ1} = V_{GSQ2} + V_{DSQ1}[...
Question: 4.SP.17

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By symmetry, $I_{DQ1} = I_{DQ2}$. KCL...
Question: 4.SP.16

## Find the equivalent of the two identical n-channel JFETs connected in parallel in Fig. 4-21. ...

Assume the devices are described by (4.2); then [l...
Question: 4.SP.25

## The amplifier of Example 4.7 has plate current iP = IP + ip = 8 + cos ωt mA  Determine (a) the power delivered by the plate supply voltage VPP, (b) the average power delivered to the load RL, and (c) the average power dissipated by the plate of the triode. (d) If the tube has a plate rating of 2 W ...

(a)   The power supplied by the source V_{P...
Question: 4.SP.13

## A p-channel MOSFET operating in the enhancement mode is characterized by VT = -3 V and IDQ = -8 mA when VGSQ = -4.5 V. Find (a) VGSQ if IDQ = -16 mA and (b) IDQ if VGSQ = -5 V. ...

(a)   Using the given data in (4.6) leads to [late...
Question: 4.SP.12

## For the n-channel enhancement-mode MOSFET of Fig. 4-18, gate current is negligible, IDon = 10 mA, and VT = 4 V. If RS = 0, R1 = 50 kΩ, VDD = 15 V, VGSQ = 3 V, and VDSQ = 9 V, determine the values of (a) R1 and (b) RD. ...

(a)    Since i_G = 0, V_{GSQ} = V_{GG}[/lat...
Question: 4.SP.11

## The n-channel enhancement-mode MOSFET of Fig. 4-18 is characterized by VT = 4 V and IDon = 10 mA. Assume negligible gate current, R1 = 50 kΩ, R2 = 0.4 MΩ, RS = 0, RD = 2 kΩ, and VDD = 15 V. Find (a) VGSQ, (b) IDQ, and (c) VDSQ. ...

(a)    With negligible gate current, (4.3) leads t...
Question: 4.SP.10

## Gate current is negligible for the p-channel JFET of Fig. 4-17. If VDD = -20 V, IDSS = -10 mA, IDQ = -8 mA, Vp0 = -4 V, RS = 0, and RD = 1.5 kΩ, find (a) VGG and (b) VDSQ. ...

(a)    Solving (4.2) for $v_{GS}$ and...