Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6 002 Circuits Electronics Spring 2007 Homework 7 Handout S07 036 Issued 03 22 2007 Due 04 06 2007 Helpful readings for this homework Chapter 8 Exercise 7 1 Exercise 8 2 from Chapter 8 of A L page 448 Exercise 7 2 Exercise 8 6 from Chapter 8 of A L page 449 Problem 7 1 VS VS R R vO vI vM ID Figure 1 A two stage non inverting MOSFET ampli er is shown above In this problem VI is chosen such that VI VM ID VO a Show that the input bias VI for which VI VM ID VO is given by V I VT 1 1 2KR VS VT KR b Draw the small signal circuit for the ampli er and use it to determine the small signal gain G vo vi Express G as a function of K VT VI and R Problem 7 2 Parts a b and c of Problem 8 2 from Chapter 8 of A L page 450 In part c determine the small signal gain in terms of gm K VIN VOU T VT 1 Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY Problem 7 3 This problem examines the behavior and application of a new eld e ect transistor NewFET with large signal electrical characteristics as described in Figure 2 Here it is assumed that vDS 0 Note that the coe cient K and the threshold voltage VT are both positive and constant iD vGS vDS Figure 2 Large signal characteristics of the NewFet a An ampli er is constructed with the NewFET as shown in Figure 3 Note that this ampli er does not have a load at its output Derive an expression for vOU T as a function of vIN in terms of the power supply voltage VS the resistance R and the NewFET parameters K and VT Do so for 0 vIN VS assuming that 0 VT VS Figure 3 The NewFet used as an ampli er b For the ampli er shown in Figure 3 and analyzed in part a sketch and clearly label a graph of vOU T versus vIN for 0 vIN VS c When the NewFET is biased into its active region its small signal model is as shown in Figure 4 Using the model shown in Figure 4 nd id in terms of gm ro vgs and vds d Assuming that the NewFET is biased into its active region derive expressions for the smallsignal model parameters gm and ro in terms of the large signal model parameters K and VT and the bias voltages VGS and VDS 2 Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY Figure 4 Small signal model of the NewFET when biased in its active region 3 Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY
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