22-03-2014, 10:05 AM
Transistor Characteristics - BJT and JFET
Aim:
1. To study the input and output characteristics of NPN/PNP transistor in common emitter
configuration and to learn the use of characteristic curves for graphical analysis of an
amplifier by drawing load line and finding Q point.
2. To obtained the drain characteristics of a JFET and draw the load line.
Procedure:
1. Make the common emitter (CE) circuit as shown in Fig. 1.1. Measure the output
characteristics i.e. IC versus V for different values of base currents IB = 0, 0.1, 0.2 mA. Do not
exceed VCE beyond 10V. Similarly measure the input characteristic IB versus VBE for VCE =0, 0.3,
0.6 and 0.9V. Plot the input and output characteristic curves for CE configurations. From the
plots determine the current gain β. Draw the static load line and determine the Q point. Obtain
transfer characteristics ie., IB vs. IC and determine current gain .
CE
2. To study the I-V characterization of the JFET, make the circuit as shown in Fig.1.2. Initially
set VGS to zero, by shorting the gate-to-source terminals or by setting VGG=0. By varying the
bias voltage VDD from 0 to 15V in steps, measure the drain current I D as a function of the voltage
drop across drain to source, VDS. Repeat the above ID versus VDS measurements for different
values of VGS namely VGS = + 0.5, -0.5, -1, -1.5, -2.0 (negative sign implies the reverse biasing
of gate terminal). Plot ID versus VDS for different values of VGS. Determine the pinch-off
voltage from the plots and the safe limit of VDS.
Aim:
1. To study the input and output characteristics of NPN/PNP transistor in common emitter
configuration and to learn the use of characteristic curves for graphical analysis of an
amplifier by drawing load line and finding Q point.
2. To obtained the drain characteristics of a JFET and draw the load line.
Procedure:
1. Make the common emitter (CE) circuit as shown in Fig. 1.1. Measure the output
characteristics i.e. IC versus V for different values of base currents IB = 0, 0.1, 0.2 mA. Do not
exceed VCE beyond 10V. Similarly measure the input characteristic IB versus VBE for VCE =0, 0.3,
0.6 and 0.9V. Plot the input and output characteristic curves for CE configurations. From the
plots determine the current gain β. Draw the static load line and determine the Q point. Obtain
transfer characteristics ie., IB vs. IC and determine current gain .
CE
2. To study the I-V characterization of the JFET, make the circuit as shown in Fig.1.2. Initially
set VGS to zero, by shorting the gate-to-source terminals or by setting VGG=0. By varying the
bias voltage VDD from 0 to 15V in steps, measure the drain current I D as a function of the voltage
drop across drain to source, VDS. Repeat the above ID versus VDS measurements for different
values of VGS namely VGS = + 0.5, -0.5, -1, -1.5, -2.0 (negative sign implies the reverse biasing
of gate terminal). Plot ID versus VDS for different values of VGS. Determine the pinch-off
voltage from the plots and the safe limit of VDS.