University of Michigan EECS 311: Electronic Circuits Fall Quiz 2 11/3/2008

Transcription

1 University of Michigan EECS 311: Electronic Circuits Fall 2008 Quiz 2 11/3/2008 NAME: Honor Code: I have neither given nor received unauthorized aid on this examination, nor have I concealed any violations of the Honor Code. Signature Problem Points Score Initials Total

2 Page 2 of 16

3 Initials: Problem 1 (26 Points): Potpourri this problem has four unrelated parts. a) Find the expression for gain / of the circuit below. Use the exact model for the diode, / 1. Assume the opamp is ideal. Page 3 of 16

4 b) Find an expression for the voltage for the circuit below assuming 0 and 0. Use the exact model for the diodes, / 1, assuming the two diodes are identical (same values for and same temperature). V DD R B i IN1 v OUT i IN2 Page 4 of 16

5 Initials: c) Identify the region of operation of in the circuit below when 2, 3, and 1. Assume 1 and ignore the body effect on threshold voltage. d) Identify the region of operation of in the circuit below when 3, 5, and 5. Assume 1 and ignore the body effect on threshold voltage. Page 5 of 16

6 Problem 2 (20 Points): parts. Use the following circuit and ignore base width modulation for all 10V 5V I B I C Q 1 1kΩ V CE 10V 3kΩ kΩ a) Substitute the simplified large signal model for the BJT in the forward active region using the constant voltage source model for the base emitter junction diode. Solve for the values of and. Page 6 of 16

7 Initials: b) Substitute the simplified large signal model for the BJT in the saturation region using the constant voltage source models for the base emitter and collector emitter voltages. Solve for the values of and. Page 7 of 16

8 c) Given your answers to parts a) and b), is in the forward active or saturation region. Page 8 of 16

9 Initials: Problem 3 (30 Points): Use the circuit shown below to answer all of the following parts. Use the constant voltage source model for the base emitter junction diode of. Ignore channel length modulation, body effect, and base width modulation for all parts. 10V 10V 500 / V BIAS M 1 50Ω 1.0 1kΩ V D I B I C V C Q a) Assuming is kept in the forward active region, find the numerical value of required to support 1. Page 9 of 16

10 b) Assuming is kept in saturation, find the numerical value of required to support from part a). c) Find the maximum value of allowed while keeping in the forward active region. Page 10 of 16

11 Initials: d) As is swept from0 to 10, the drain voltage follows the graph shown below. Label the regions on the graphs where is in cutoff, linear, and saturation, specifically showing the values of at the boundaries between regions. V D V BIAS Page 11 of 16

12 e) Sketch the voltage at node as is swept from0 to 10. Use the graph from part d), giving you as is swept over the same range, to generate your sketch. Label the regions on the graph where is in off, forward active, and saturation. V C V BIAS Page 12 of 16

13 Initials: Problem 4 (24 Points): A non linear two terminal device M has the following I V relationship, given in an expression and also plotted. Use this device to answer the following questions about small signal analysis. v M M i M 0.01 im [ma] DC Bias Point [V] v M a) Derive an expression for the small signal conductance /, linearized around a DC operating point defined by variables and. Page 13 of 16

14 b) Complete the small signal model by drawing the circuit element in the box that should be used to model the device in small signal. Evaluate the value of this element at the bias current of 40 as shown in the graph above. Page 14 of 16

15 Initials: c) The device is used in the following circuit. Draw the complete small signal circuit, substituting the model for the device found in part b). Assume is a DC bias current. Page 15 of 16

16 (Space for additional work) Page 16 of 16