Determine the α rating of the transistor. 10 (ii) shows the various currents and voltages along with polarities. 10 (i) shows the transistor circuit while Fig. The transistor is of silicon and has β = 150. Q17. Determine V CB in the transistor circuit shown in Fig. I CBO) is multiplied by β in the collector as shown in Fig. When the transistor is in CE arrangement, the base current (i.e. The leakage current ICBO is the current that flows through the base-collector junction when emitter is open as shown is Fig. Q16. Using diagrams, explain the correctness of the relation I CEO = (β 1)I CBO. For a certain transistor, I B = 20 μA I C = 2 mA and β = 80. The transistor is connected in CB arrangement, what will be the leakage current? Given that β = 120. Q14. The collector leakage current in a transistor is 300 μA in CE arrangement. A small leakage current I CBO flows due to minority carriers. When the emitter circuit is open as shown in Fig.7 (i), the collector-base junction is reverse biased. Find α, I E and I B when collector current is 1 mA. When the base is disconnected and the same voltage is applied between collector and emitter, the current is found to be 20 μA. With collector positive, a current of 0.2 μA flows. A voltage of 5 V is applied between collector and base. Q13. An n-p-n transistor at room temperature has its emitter disconnected. 6 shows the required common emitter connection with various values. If α = 0.96, determine : (i) collector-emitter voltage (ii) base current. Q12. A transistor is connected in common emitter (CE) configuration in which collector supply is 8 V and the voltage drop across resistance R C connected in the collector circuit is 0.5 V. The voltage drop across RC (= 1 kΩ) is 1 volt. 5 shows the required common emitter connection. Find the base current for common emitter connection. Q11. For a transistor, β = 45 and voltage drop across 1kΩ which is connected in the collector circuit is 1 volt. 8.20 shows the conditions of the problem. Hence determine the value of I C using both α and β rating of the transistor.įig. Q10. Find the α rating of the transistor shown in Fig. Q9. Calculate I E in a transistor for which β = 50 and I B = 20 μA. Since the transistor is of silicon, V BE = 0.7V.Īpplying Kirchhoff’s voltage law to the emitter-side loop,we get,Īpplying Kirchhoff’s voltage law to the collector-side loop, we have, The other two are the Common BaseĪnd Common Collector circuit configurations.Q7. For the common base circuit shown in Fig. The Common Emitter BJT Amplifier is one of three single BJT circuit configurations. Voltage amplifier involves the AC analysis of the circuit. When a small signal source is connected to the base of the transistor instead of a on/off DC source, the circuit is aĬommon emitter amplifier. When a high current amplification is required, a darlington Output voltage when the transistor is switched off. When an inductive load is connected to the collector, a recirculation diode is required across the load to damp the In this operation the collector current I C is determined using In a real transistor V CE never reaches 0, instead it saturates at around 0.1V.To reduce this base current is to use a Darlington transistor. Need a sufficiently large base current to operate the BJT as a switch (observe the problem when R1=10K). If you have a small load (R2=100 ohm), you will Change the values of R1 and R2 and press the Simulate button.Assume β=100, and use equation 6 to calculate V CE.Observe the node voltages when you change VIN by adjusting the knob.Substitute equation \ref and I C is no longer dependent on I B The transistor current gain provides the order of magnitude increase in collector current.įirst we redraw the schematic using the BJT DC equivalent This is required when the typical digital output (maxĬurrent output 20ma) does not provide sufficent current drive for high current devices like lamps, solenoids or The Bipolar Junction Transistor can be used as a switch.
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