ECEN 2250 Introduction to Circuits & Electronics Fall 201110-31-11 P. MathysProblem Set 9 (Solutions are due Fri. 11-04-11)Note: For all problems you have to explain how you arrived at the solution legibly and ina logical order. This includes (i) Statement of problem, (ii) strategie(s) for solution, (iii)execution of the strategy, identifying each step and including a check of the solution(s), and(iv) logical and legible presentation and clear identification of the solution.1) Problem 4-14 in the book.2) Consider the following bipolar junction transistor circuits. Assume that the transistorsare in active mode (vCE> 0.4 V and iC> 0) and use the non-linear transistor model (basedon the Shockley equation) unless stated otherwise.(a) The transistor in circuit (a) has β = 120 and vBEwas measured as 0.7 V at iC= 5 mA.Select RCand REsuch that iC= 100 mA and vC= 8 V. What is the value of vEin thiscase?(b) Determine the voltage gain dvO/dvSin terms of R, iCand vTfor the (b) circuit.(c) The circuit in (c) sinks a constant current iCas long as the transistor is in active mode.Determine iCin terms of VCC, R1, R2, RE, vBE, and β. Use the linear current-controlledcurrent source model for this circuit.3) Consider the pnp transistor circuits shown below. Assume tht the transistors are in activemode and use the linear transistor model with vEB= 0.7 V unless otherwise stated.1(a) For VCC= 15 V and β = 80, find values for RBand RCin circuit (a) such that iE= 10mA and vC= 5 V.(b) For the circuit and values you found in (a), determine vCand iEas β → ∞ and iB→ 0(while keeping vEB= 0.7 V so that the transistor is in the active mode).(c) To improve the situation that you saw in part (b) for the case when a transistor has ahigh β, the c ircuit in figure (b) is proposed. Choose ix≈ iBand determine Rx, RB, andRCsuch that iE= 10 mA and vC= 5 V. Now, what happens to vCand iEas β → ∞ andiB→ 0 (while keeping vEB= 0.7 V so that the transistor is in the active mode).4) Use the following circuit in LTs pice to determine the parameters iS, α and β of the defaultnpn bipolar junction transistor model NP N (i.e., without choosing a particular transistortype).Assume that iE= iS(evBE/vT− 1) ≈ iSevBE/vT, where iEis the emitter current, vBEis thebase-emitter voltage, iSis the reverse saturation current, and vT= 25.7 mV (at 25◦C) is thethermal voltage. For α use α = iC/iEand for β use β = iC/iB.c2001–2011, P. Mathys. Last revised: 11-06-11,