1Massachusetts Institute of TechnologyDepartment of Electrical Engineering and Computer Science6.002 – Electronic CircuitsFall 2003Quiz 1• Please write your name on each page of the exam in the space provided, and circle the nameof your recitation instructor and the time of your recitation at the bottom of this page.• Please verify that there are 14 pages in your exam.• To the extent possible, do all of your work on the pages contained within this exam. Inparticular, try to do your work for each question within the boundaries of the question, or onthe back side of the page preceding the question. Extra pages are also available at the end ofyour exam.• You may use one double-sided page of notes and a calculator while taking this exam.• Good luck!Problem Points Score Grader1 202 203 154 255 20Total 100Name:Instructor: Perreault Antoniadis Chaniotakis Umans KolodziejskiTime: 10 11 11 11 12 12 1 2 3Name: 2Problem 1 – 20 Points2 Ω2 Ω3V6A4 ΩAB16 Ω4 Ω12 Ω4 Ω4 Ω4 Ω8 Ω8 Ω(A) Determine the values of R1, R2and R3so that the entire circuit above is equivalent to thesimpler circuit shown below for the purpose of creating the Norton equivalent of the above circuitwhen viewed from its port labeled A-B. R33V6AAB R2 R1R1= R2= R3=(over)Name: 3(B) Assuming R1= R2= R3= 8Ω in the circuit in Part (A), draw the Norton equivalent of thecircuit when viewed from its A-B port. Note that these may not be the values you obtained in Part(A). (Be sure to specify element values, units and polarities.)Name: 4Problem 2 – 20 PointsThe zener diode in the circuit below has the v-i characteristic shown at the right.vSiD3 kΩ7 kΩSviD+-iDvD(volts)0.6-4.50(A) For the input voltage vSshown below, indicate the time intervals where the diode is ON(conducting a current) and OFF (open circuit). Label the boundaries with numerical values on theplot below.20-2010 20 30 40vS(t) (volts)t (ms)Name: 5(B) For the input voltage vSshown in Part (A), sketch the zener diode voltage waveform, vD(t).Label all breakpoint coordinates with values and units.10 20 30 40vD(t) (volts)t (ms)Name: 6Problem 3 – 15 Points(A) The digital circuit below has logic inputs P1, P2, ... Pn, S1, S2, ... Smand output X. Assumingthat the element values are chosen so that the circuit satisfies a static discipline, what is the logicfunction computed by the circuit? RLP1P2P3Pn. . .XS1S2S3SmVS. . .X =(B) For what choice of logic input values is the maximum power consumed by the circuit? Assumethat all the MOSFETs have a nonzero value for their ON resistance.Name: 7Problem 4 – 25 PointsThe semiconductor device team at Yenron Inc. has created a remarkable new device called theLOSFET. The symbol for the device and its equivalent circuit model are shown below.GiDSDSvGS+--+vDSGiDSDSvGS< 2V-+vDS1mAiDSDS-vDSG+vGS> 2V1k ΩvGS+-vGS+-Like the MOSFET studied in 6.002, the LOSFET has three terminals labeled G (gate), D(drain), and S (source). When vGS< 2V , the device displays an open circuit between its D and Sterminals, and when vGS≥ 2V , the device behavior between its D and S terminals can be modeledby a 1mA current source in parallel with a 1kΩ resistor. The current into the gate G is always 0.(A) Plot the iDSversus vDScurve for the LOSFET when vGS< 2V in the range −5V ≤ vDS≤ +5V .iDS(mA)vDS(volts)01 2 3 4 5-1-2-3-4-5Name: 8(B) Plot the iDSversus vDScurve for the LOSFET when vGS≥ 2V in the range −5V ≤ vDS≤ +5V .Clearly mark all relevant intercept values on the two axes.iDS(mA)vDS(volts)01 2 3 4 5-1-2-3-4-5Name: 9(C) Yenron engineers use the LOSFET to build the inverter circuit shown below.GDSvIN+--+vOUTVSRLAssuming that VS= 4V and RL= 1kΩ, determine vOU Tfor (i) vIN= 0V and (ii) vIN= 4V .(Remember that the LOSFET turns ON for vGS≥ 2V .)(i) vIN= 0V, vOU T= (ii) vIN= 4V, vOU T=Name: 10(D) Yenron develops several inverters using the same LOSFET but with various values of VSandRL. One of the inverters produces a high output of vOU T= 5V and a low output of vOU T= 1V .(Note that although this inverter has the same internal circuit as the inverter described earlier, thisinverter has different values of RLand VS).Determine whether this inverter satisfies a static discipline with the following voltage thresholds:VOH= 3.5V , VOL= 0.5V , VIH= 2.5V , and VIL= 1.9V . (Simply answer yes if it satisfies thestatic discipline. If your answer is no, indicate a threshold that is not met by the device.)(E) Next, determine whether the inverter in Part (D) satisfies a static discipline with the followingvoltage thresholds: VOH= 3.0V , VOL= 1.5V , VIH= 1.9V , and VIL= 1.7V . (Simply answer yesif it satisfies the static discipline. If your answer is no, indicate a threshold that is not met by thedevice.)Name: 11Problem 5 – 20 Points(A) Yikes, Inc. has developed the new device shown below that requires the application of voltagesin the range 0V to 3V at its A-B port.ABThe Yikes engineers rummage through their supply room but cannot find an appropriate variablevoltage source, rather they find only one 9V battery and several 1kΩ fixed and variable resistors.(A 1kΩ variable resistor can vary between 0Ω and 1kΩ). Symbols for these elements are shownbelow.9V9V battery1k Ω1k Ω1k Ω1k Ω variableresistorresistor(many (manyavailable) available)(only oneavailable)You are called in as a 6.002 expert to help the Yikes engineers. The Yikes engineers also tellyou that the resistance looking into the A-B port of the device is infinite. Design a circuit that cansupply voltages in the exact range 0V to 3V using only the circuit elements in the supply room.Clearly mark the terminals in your circuit which must be connected to the A-B port of the device.Name: 12(B) Always looking to help your client, you notice that the device would work even better if voltagesin the exact range −3V to +3V were applied at its A-B port. Design a circuit that can supply thesevoltages using only the elements available in the supply room. (Hint: Try producing two separatevoltages, v1and v2, that can be varied independently such that v1− v2produces the desired outputvoltage.)(End)Name: 13Name:
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