BJT INPUT CHARACTERISTICS

BJT INPUT CHARACTERISTICS

BJT INPUT CHARACTERISTICS – Common Base Configuration
Download BJT Common Base Input CHARA.epb

Aim

1.To simulate the BJT input characteristics in common base configuration.

Components Required

Transistor - BC107A (1) Resistor – RC05 (2) DC Voltage source - VDC (3) Ground - SPL0(1)

Circuit Diagram

Procedure

Draw the circuit diagram after loading components from library. A DC source (VDC/2) with 0 V is placed as the dummy voltage source to obtain the current waveform. Wiring and proper net assignment has been made. The circuit is preprocessed. The VI characteristics may be obtained by performing DC Transfer function Analysis. Place the current waveform marker at the positive terminal of the dummy voltage source VDC/2 (Voltage = 0 Volts).

For placing waveform markers, select Tools → Instruments → set wave form Contents → Currect waveform → Click on the required net and place the waveform marker. The sweep parameter (voltage) for input source is set in the Analysis window. The applied voltage is swept from an initial value to final value with the steps provided. To get VI characteristics, the currents corresponding to varying input voltages are noted. The VI graph is observed in the Waveform Viewer.

To proceed with the simulation, the steps are as follows

1.Select Tools → Components → Component properties→ Change simulation parameters→ Click on the required component and change its values.

2.The values to be provided to the components are

Transistor : BC107A (Click on the Set up Model of the Model Type. Click on Accept to get the default values assigned)

Resistors : R1 = 100 Ohm, R2 = 100 Ohm

VDC/1 : 10V

VDC/2 : 0V

VDC/3 : 10V

Note: For input/output characteristics plot of BJT, FET, MOS etc, it is not necessary to place a waveform marker in the diagram. Its because the sweep variable of the VI parameters are being plotted. The current through a net can be obtained by enabling the Vx#branch in the waveform. Please ensure the connectivity of dummy voltage source having (0V) for obtaining the direction of current.

3.For setting up simulation time and analysis types select Simulation menu choose Analysis. In the window pops up, select DC Transfer function analysis from tree view.

4.Enter following values:

First Source : VDC/1 [V2]
Start voltage : 0V
Stop voltage : 5V
Step : 5m
Results : Select waveform from drop down menu.

5.Click on Accept.

6. Expand the DC transfer function and select Waveform viewer.

7. Select dummy voltage source branch.

8. Click on Accept.

9.Select DC Transfer function analysis.

10.Run Analysis by clicking on Run button.

Result