ch10

ch10 - SOLUTIONS CHAPTER 10 10.1 For an npn transistor with...

Info icon This preview shows pages 1–5. Sign up to view the full content.

SOLUTIONS CHAPTER 10 10.1 For an npn transistor with ' 19 3 10 DE N cm - = , ' 17 3 2 10 AB N cm - = × , ' 16 3 5 10 DC N cm - = × , 0.13 E W m μ = , and 0.15 B W m μ = under the bias conditions of 20 B I A μ = and 2.5 BC V V = - , find a) β b) I C c) r π d) g m e) ( ) BE C C π f) C μ g) f co h) f T Note that band gap narrowing should be accounted for, and that both sides of the E-B junction are short. Let the area of the emitter junction be A E =2.5 × 10 -7 cm - 2 and the area of the collector junction be A C =8 × 10 -7 cm -2 . a) To find β , we use Equation (9.43) and from Figure 2.25, * 50 g E meV = . Then * ' g E C nB E kT AB pE B N D W e N D W β - ∆ = From Figure 3.11, we find D pE 3.8, and D nB 13 cm -2 /s. The widths are W E =0.13 μ m and W B =0.15 μ m. * ' 0.05 19 0.026 17 2.86 10 13 0.15 2 10 3.8 0.13 83 g E C nB E kT AB pE B N D W e N D W e β - ∆ - = × = × = Anderson & Anderson 1 November 19, 2007 Chapter 10: Solutions
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

b) Ι C Since , C B I I β = 83x20 1.7 . C I A mA μ = = c) r π 6 0.026 1300 20 10 B kT r qI π - = = = × d) g m From Equation 10.15 83 64 1300 m g mS r π β = = = e) C π For a BJT operating in the active mode, scEB jEB C C ? and we can approximate scBE C C π 2245 . From Equation 10.30 for constant base doping, the stored charge capacitance is ( 29 ( 29 ( 29 ( 29 2 4 2 13 2 0.13 10 83 2.4 10 0.24 3 3 15 / 1300 B sc nB cm W C F pF D r cm s π β - - × = = = × = f) C μ The capacitance C μ is just the BC junction capacitance. This is not a one- sided junction, so the result is: Anderson & Anderson 2 November 19, 2007 Chapter 10: Solutions
Image of page 2
( 29 ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 1 2 1 19 14 17 3 16 3 2 7 2 17 16 -14 2 1.6 10 11.8 8.85 10 / 2 10 5 10 8 10 2 2 10 5 10 0.83 2.5 2.5x10 0.025 A D jBC A D bi a q N N C C A N N V V F cm cm cm cm F pF μ ε - - - - - = = + - × × × × = × × + × - - = = where we found the value of V biBC from ( 29 ' ' 17 16 2 2 10 2x10 5 10 ln 0.026ln 0.83 1.08 10 A D bi i N N kT V V q n × = = = × g) f co The cutoff frequency for this transistor is, from Equation (10.37), ( 29 ( 29 ( 29 13 14 1 1 462 2 2 1300 2.4 10 2.5 10 co be f MHz r C C F π μ π π - - = = = + × + × h) f T From Equation (10.38), ( 29 ( 29 6 9 83 462 10 38 10 Hz 38GHz T DC co f f β = = × = × = 10.2. For the transistor of Problem 10.1, plot i c i b as a function of frequency. What is the unity-gain frequency? We use 2 2 6 83 1 1 462 10 c b co i i f f f β = = + + × and plot against frequency. Anderson & Anderson 3 November 19, 2007 Chapter 10: Solutions
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Note that from the plot, 38 T f GHz = in agreement with the result from Problem 10.1h.
Image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.
  • '
  • NoProfessor
  • Bipolar junction transistor, Anderson chapter

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern