Question: Repeat Problem 15 for T = 100°C (

> Given that Eg = 0.67 eV for germanium, find the wavelength of peak solar response for the material. Do the photons at this wavelength have a lower or higher energy level?

> Consult your reference library and determine the level of Eg for GaP, ZnS, and GaAsP, three semi- conductor materials of practical value. In addition, determine the written name for each material.

> Referring to Fig. 1.52e, what would appear to be an appropriate value of VK for this device? How does it compare to the value of VK for silicon and germanium?

> Compare the levels of dynamic impedance for the 24-V diode of Fig. 1.48b at current levels of 0.2, 1, and 10 mA. How do the results relate to the shape of the characteristics in this region?

> Determine the dynamic impedance for the 24-V diode at IZ = 10 mA for Fig. 1.48b. Note that it is a log scale.

> Using the curves of Fig. 1.48a, what level of temperature coefficient would you expect for a 20-V diode? Repeat for a 5-V diode. Assume a linear scale between nominal voltage levels and a current level of 0.1 mA.

> Determine the temperature coefficient of a 5-V Zener diode (rated 25°C value) if the nominal voltage drops to 4.8 V at a temperature of 100°C.

> At what temperature will the 10-V Zener diode of Fig. 1.47 have a nominal voltage of 10.75 V? (Note the data in Table 1.7.)

> The following characteristics are specified for a particular Zener diode: VZ = 29 V, VR = 16.8 V, IZT = 10 mA, IR = 20 mA, and IZM = 40 mA. Sketch the characteristic curve in the manner displayed in Fig. 1.47.

> Using the characteristics of Fig. 1.37, determine the temperature at which the diode current will be 50% of its value at room temperature (25°C).

> Using the characteristics of Fig. 1.37, determine the maximum power dissipation levels for the diode at room temperature (25°C) and 100°C. Assuming that VF remains fixed at 0.7 V, how has the maximum level of IF changed between the two temperature levels

> For the diode of Fig. 1.37, determine the maximum ac (dynamic) resistance at a forward cur- rent of 0.1, 1.5, and 20 mA. Compare levels and comment on whether the results support con- clusions derived in earlier sections of this chapter.

> If 48 eV of energy is required to move a charge through a potential difference of 3.2 V, deter- mine the charge involved.

> For the diode of Fig. 1.37 determine the level of IR at room temperature (25°C) and the boiling point of water (100°C). Is the change significant? Does the level just about double for every 10°C increase in temperature?

> Does the reverse saturation current of the diode of Fig. 1.37 change significantly in magnitude for reverse-bias potentials in the range —25 V to —100 V?

> a. Comment on the change in capacitance level with increase in reverse-bias potential for the diode of Fig. 1.37. b. What is the level of C(0)? c. Using VK = 0.7 V, find the level of n in Eq. 1.9.

> Plot IF versus VF using linear scales for the diode of Fig. 1.37. Note that the provided graph employs a log scale for the vertical axis (log scales are covered in Sections 9.2 and 9.3).

> Sketch the waveform for i of the network of Fig. 1.57 if tt = 2ts and the total reverse recovery time is 9 ns. FIG. 1.57 Problem 45.

> Find the applied reverse bias potential if the transition capacitance of a silicon diode is 4 pF but the no-bias level is 10 pF with n = 1>3 and VK = 0.7 V.

> The no-bias transition capacitance of a silicon diode is 8 pF with VK = 0.7 V and n = 1>2. What is the transition capacitance if the applied reverse bias potential is 5 V?

> Determine the reactance offered by a diode described by the characteristics of Fig. 1.33 at a forward potential of 0.2 V and a reverse potential of —20 V if the applied frequency is 6 MHz.

> Describe in your own words how diffusion and transition capacitances differ.

> Referring to Fig. 1.33, determine the diffusion capacitance at 0 V and 0.25 V.

> a. How much energy in joules is required to move a charge of 12 mC through a difference in potential of 6 V? b. For part (a), find the energy in electron-volts.

> a. Referring to Fig. 1.33, determine the transition capacitance at reverse-bias potentials of —25 V and —10 V. What is the ratio of the change in capacitance to the change in voltage? b. Repeat part (a) for reverse-bias potentials of —10 V and —1 V. D

> Find the piecewise-linear equivalent circuit for the germanium and gallium arsenide diodes of Fig. 1.18.

> Repeat Problem 36 for the diode of Fig. 1.27.

> Find the piecewise-linear equivalent circuit for the diode of Fig. 1.15. Use a straight-line seg- ment that intersects the horizontal axis at 0.7 V and best approximates the curve for the region greater than 0.7 V.

> Determine the ac resistance for the diode of Fig. 1.15 at 0.75 V and compare it to the average ac resistance obtained in Problem 34.

> Determine the average ac resistance for the diode of Fig. 1.15 for the region between 0.6 V and 0.9 V.

> Using Eq. (1.6), determine the ac resistance at a current of 1 mA and 15 mA for the diode of Fig. 1.15. Modify the equation as necessary for low levels of diode current. Compare to the solutions obtained in Problem 32.

> Using Eq. (1.5), determine the ac resistance at a current of 1 mA and 15 mA for the diode of Fig. 1.15. Compare the solutions and develop a general conclusion regarding the ac resistance and increasing levels of diode current.

> a. Determine the dynamic (ac) resistance of the commercially available diode of Fig. 1.15 at a forward current of 10 mA using Eq. (1.5). b. Determine the dynamic (ac) resistance of the diode of Fig. 1.15 at a forward current of 10 mA using Eq. (1.6). c.

> Calculate the dc and ac resistances for the diode of Fig. 1.15 at a forward current of 10 mA and compare their magnitudes.

> Determine the value of R for the circuit of Fig. 2.153 that will result in a diode current of 10 mA if E = 7 V. Use the characteristics of Fig. 2.152b for the diode.

> Determine the static or dc resistance of the commercially available diode of Fig. 1.15 at a reverse voltage of —10 V. How does it compare to the value determined at a reverse voltage of —30 V?

> Repeat Problem 27 at a forward current of 15 mA and compare results.

> Determine the static or dc resistance of the commercially available diode of Fig. 1.15 at a for- ward current of 4 mA.

> What is the one important difference between the characteristics of a simple switch and those of an ideal diode?

> Describe in your own words the characteristics of the ideal diode and how they determine the on and off states of the device. That is, describe why the short-circuit and open-circuit equiva- lents are appropriate.

> Describe in your own words the meaning of the word ideal as applied to a device or a system.

> Determine the forward voltage drop across the diode whose characteristics appear in Fig. 1.19 at temperatures of —75°C, 25°C, 125°C and a current of 10 mA. For each temperature, determine the level of saturation current. Compare the extremes of each and

> Compare the characteristics of a silicon and a germanium diode and determine which you would prefer to use for most practical applications. Give some details. Refer to a manufacturer’s listing and compare the characteristics of a germanium and a silicon

> In the reverse-bias region the saturation current of a silicon diode is about 0.1 mA (T = 20°C). Determine its approximate value if the temperature is increased 40°C.

> a. Plot the function y = ex for x from 0 to 10. Why is it difficult to plot? b. What is the value of y = ex at x = 0? c. Based on the results of part (b), why is the factor —1 important in Eq. (1.2)?

> In your own words, define an intrinsic material, a negative temperature coefficient, and cova- lent bonding.

> Given a diode current of 6 mA, VT = 26 mV, n = 1, and Is = 1 nA, find the applied voltage VD.

> Given a diode current of 8 mA and n = 1, find Is if the applied voltage is 0.5 V and the tem- perature is room temperature (25°C).

> a. Using Eq. (1.2), determine the diode current at 20°C for a silicon diode with n = 2, Is = 0.1 mA at a reverse-bias potential of -10 V. b. Is the result expected? Why?

> a. Determine the thermal voltage for a diode at a temperature of 20°C. b. For the same diode of part (a), find the diode current using Eq. 1.2 if Is = 40 nA, n = 2 (low value of VD), and the applied bias voltage is 0.5 V.

> Find the saturation current (ICsat) for the fixed-bias configuration of Fig. 4.118.

> Given the information appearing in Fig. 4.120, determine: a. IC. b. VCC. c. . d. RB.

> Given the information appearing in Fig. 4.119, determine: a. IC. b. RC. c. RB. d. VCE.

> For the fixed-bias configuration of Fig. 4.118, determine: a. IBQ. b. ICQ. c. VCEQ. d. VC. e. VB. f. VE.

> Given the information provided in Fig. 4.123, determine: a. RC. b. RE. c. RB. d. VCE. e. VB.

> a. Draw the load line for the network of Fig. 4.122 on the characteristics of Fig. 4.121 using  from problem 8 to find IBQ. b. Find the Q-point and resulting values ICQ and VCEQ. c. Find the value of  at the Q-point. d. How does the value of part (c) c

> For the emitter-stabilized bias circuit of Fig. 4.122, determine: a. IBQ. b. ICQ. c. VCEQ. d. VC. e. VB. f. VE.

> If the base resistor of Fig. 4.118 is increased to 910 kΩ, find the new Q-point and resulting values of ICQ and VCEQ.

> a. Ignoring the provided value of (120) draw the load line for the network of Fig. 4.118 on the characteristics of Fig. 4.121. b. Find the Q-point and the resulting ICQ and VCEQ. c. What is the beta value at this Q-point?

> Describe how you will remember the forward- and reverse-bias states of the p–n junction diode. That is, how will you remember which potential (positive or negative) is applied to which terminal?

> Given the BJT transistor characteristics of Fig. 4.121: a. Draw a load line on the characteristics determined by E = 21 V and RC = 3 kΩ for a fixed-bias configuration. b. Choose an operating point midway between cutoff and saturation. Determine the value

> What is the source of the leakage current in a transistor?

> How must the two transistor junctions be biased for proper transistor amplifier operation?

> What is the major difference between a bipolar and a unipolar device?

> a. Using the characteristics of Fig. 3.24, determine ac at IC = 14 mA and VCE = 3 V. b. Determine dc at IC = 1 mA and VCE = 8 V. c. Determine ac at IC = 14 mA and VCE = 3 V. d. Determine dc at IC = 1 mA and VCE = 8 V. e. How does the level of ac and

> Using the characteristics of Fig. 3.23c, determine the level of dc at IC = 10 mA at the three levels of temperature appearing in the figure. Is the change significant for the specified tem- perature range? Is it an element to be concerned about in the d

> Using the characteristics of Fig. 3.23b, determine how much the level of hfe has changed from its value at 1 mA to its value at 10 mA. Note that the vertical scale is a log scale that may require reference to Section 11.2. Is the change one that should b

> Using the characteristics of Fig. 3.23d, determine whether the input capacitance in the common- base configuration increases or decreases with increasing levels of reverse-bias potential. Can you explain why?

> How does the range of hFE (Fig. 3.23c, normalized from hFE = 100) compare with the range of hfe (Fig. 3.23b) for the range of IC from 0.1 to 10 mA?

> Based on the data of Fig. 3.23, what is the expected value of ICEO using the average value of dc?

> Determine Vo and ID for the network of Fig. 2.163.

> Using the information provided in Fig. 3.23 regarding PDmax, VCEmax, ICmax and VCEsat, sketch the boundaries of operation for the device.

> Referring to Fig. 3.23, determine the temperature range for the device in degrees Fahrenheit.

> Determine the region of operation for a transistor having the characteristics of Fig. 3.8 if ICmax = 7 mA, BVCBO = 20 V, and PCmax = 42 mW.

> Determine the region of operation for a transistor having the characteristics of Fig. 3.13 if ICmax = 6 mA, BVCEO = 15 V, and PCmax = 35 mW.

> For a transistor having the characteristics of Fig. 3.13, sketch the input and output characteris- tics of the common-collector configuration.

> An input voltage of 2 V rms (measured from base to ground) is applied to the circuit of Fig. 3.21. Assuming that the emitter voltage follows the base voltage exactly and that Vbe (rms) = 0.1 V, calculate the circuit voltage amplification (Av = Vo/Vi) and

> a. Given that dc = 0.980, determine the corresponding value of dc. b. Given dc = 120, determine the corresponding value of a. c. Given that dc = 120 and IC = 2.0 A, find IE and IB.

> Using the characteristics of Fig. 3.13a, determine dc at IB = 25 A and VCE = 10 V. Then calculate dc and the resulting level of IE. (Use the level of IC determined by IC = dcIB.)

> a. Using the characteristics of Fig. 3.13a, determine ac at IB = 60 A and VCE = 4 V. b. Repeat part (a) at IB = 30 A and VCE = 7 V. c. Repeat part (a) at IB = 10 A and VCE = 10 V. d. Reviewing the results of parts (a) through (c), does the value of 

> a. Using the characteristics of Fig. 3.13a, determine dc at IB = 60 A and VCE = 4 V. b. Repeat part (a) at IB = 30 A and VCE = 7 V. c. Repeat part (a) at IB = 10 A and VCE = 10 V. d. Reviewing the results of parts (a) through (c), does the value of 

> Determine Vo1, Vo2, and I for the network of Fig. 2.162.

> a. Using the characteristics of Fig. 3.13a, determine ICEO at VCE = 10 V. b. Determine dc at IB = 10 A and VCE = 10 V. c. Using the dc determined in part (b), calculate ICBO.

> a. For the common-emitter characteristics of Fig. 3.13, find the dc beta at an operating point of VCE = 6 V and IC = 2 mA. b. Find the value of a corresponding to this operating point. c. At VCE = +6 V, find the corresponding value of ICEO. d. Calculate

> Using the characteristics of Fig. 3.13: a. Find the value of IC corresponding to VBE = +750 mV and VCE = +4 V. b. Find the value of VCE and VBE corresponding to IC = 3.5 mA and IB = 30 A.

> a. Given an adc of 0.998, determine IC if IE = 4 mA. b. Determine adc if IE = 2.8 mA, IC = 2.75 mA and ICBO = 0.1 A.

> a. Using the characteristics of Figs. 3.7 and 3.8, determine IC if VCB = 5 V and VBE = 0.7 V. b. Determine VBE if IC = 5 mA and VCB = 15 V. c. Repeat part (b) using the characteristics of Fig. 3.10b. d. Repeat part (b) using the characteristics of Fig. 3

> a. Using the characteristics of Fig. 3.8, determine the resulting collector current if IE = 3.5 mA and VCB = 10 V. b. Repeat part (a) for IE = 3.5 mA and VCB = 20 V. c. How have the changes in VCB affected the resulting level of IC? d. On an approximate

> a. Determine the average ac resistance for the characteristics of Fig. 3.10b. b. For networks in which the magnitude of the resistive elements is typically in kilohms, is the approximation of Fig. 3.10c a valid one [based on the results of part (a)]?

> Using the characteristics of Fig. 3.7, determine VBE at IE = 5 mA for VCB = 1, 10, and 20 V. Is it reasonable to assume on an approximate basis that VCB has only a slight effect on the rela- tionship between VBE and IE?

> If the emitter current of a transistor is 8 mA and IB is 1/100 of IC, determine the levels of IC and IB.

> Which of the transistor currents is always the largest? Which is always the smallest? Which two currents are relatively close in magnitude?

> Repeat Problem 10, but insert an impurity of indium.

> a. Using the characteristics of Fig. 2.152b, determine ID and VD for the circuit of Fig. 2.153. b. Repeat part (a) with R = 0.47 kΩ. c. Repeat part (a) with R = 0.68 kΩ. d. Is the level of VD relatively close to 0.7 V in each case? How do the resulting l

> a. Using the characteristics of Fig. 2.152b, determine ID, VD, and VR for the circuit of Fig. 2.152a. b. Repeat part (a) using the approximate model for the diode, and compare results. c. Repeat part (a) using the ideal model for the diode, and compare r

> Determine the required PIV ratings of the diodes of Fig. 2.123 in terms of the peak secondary voltage Vm.

> Determine the voltage available from the voltage doubler of Fig. 2.123 if the secondary voltage of the transformer is 120 V (rms).

> Sketch the output of the network of Fig. 2.145 if the input is a 50-V square wave. Repeat for a 5-V square wave.

> Design a voltage regulator that will maintain an output voltage of 20 V across a 1-kΩ load with an input that will vary between 30 V and 50 V. That is, determine the proper value of RS and the maximum current IZM.

> For the network of Fig. 2.188, determine the range of Vi that will maintain VL at 8 V and not exceed the maximum power rating of the Zener diode.