[SOLVED] VE311 Homework 3

Note:

(1) Please use A4 size papers.

(2) Please use the SPICE model below for simulation.

.model Qbreakn NPN IS=4e-16 BF=100 VAF=50

1. [BJT Forward-Active I-V Characteristics] For a npn BJT circuit as below:

1. (a)  [20%] When VBE = 0.7 V and VCE = 2 V , use proper equations provided in the course slides and the spice model above to calculate

   the gm and ro.

2. (b)  [10%] In Pspice, when VCE = 2 V , plot IC versus VBE (increasing

   from 0 to 1 V). Find out the slope at VBE = 0.7 V and compare it with

   the gm value calculated in (a).

3. (c)  [10%] In Pspice, when VBE = 0.7 V, plot IC versus VCE (increasing

   from 1 to 3 V). Find out the inverse of the slope atVCE =2Vand compare it with the ro value calculated in (a).

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2. [BJT Common-Emitter Amplifier] For a npn BJT circuit as below:

1. (a)  [30%] When VIN = 0.7 V , use proper equations provided in the course slides and the spice model above to calculate the small-signal

   voltage gain (Aυ = υout). Hint: take Early Effect into consideration. υin

2. (b)  [15%, DC Sweep] In Pspice, plot VOUT versus VIN (increasing from 0 to 1 V). Find out the slope at VIN = 0.7 V and compare it with the voltage gain calculated in (a).
3. (c)  [15%, Transient Analysis] In Pspice, when Vin = 0.7 + 0.001 ∙ sin(2π100 ∙ time) V, plot Vout and Vin versus time (from 0 to 0.1

   second). Find out |Aυ| = |υout| and compare it with the voltage gain υin

   calculated in (a).

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