Part A: Construct The Circuit Shown In Figure 1

Part Aconstruct The Circuit Shown In Figure 1 Below With The Parameter

Part A: Construct the circuit shown in Figure 1 below with the parameters specified in the circuit.

Part B: Calculate the following values: V_E, I_E, V_RC, V_C, V_CE.

Part C: Measure the following values: V_E, I_E, V_RC, V_C, V_CE.

Part D: Compare Part B with Part C and explain any differences.

Part E: If V_B reduces to 0.5 V, predict whether the values for the parameters in Part B will increase or decrease. Justify your prediction.

Part F: Based on your observations and measurements, describe your conclusion about this lab.

Paper For Above instruction

Part Aconstruct The Circuit Shown In Figure 1 Below With The Parameter

Part Aconstruct The Circuit Shown In Figure 1 Below With The Parameter

The laboratory exercise begins with constructing the transistor circuit as depicted in Figure 1. Utilizing the specified parameters—such as resistor values, supply voltages, and transistor type—the circuit must be assembled on a breadboard or appropriate circuit board. Ensuring correct connections is vital to achieve accurate measurements and analysis. Attention to detail includes verifying the orientation of the transistor, proper connections of the collector, base, and emitter terminals, as well as the placement of all resistors and power supply connections.

Calculation of Circuit Parameters (Part B)

The subsequent step involves calculating key electrical parameters based on the circuit's configuration and component specifications. For instance, calculating the emitter voltage (V_E) requires knowledge of the base-emitter junction voltage and the biasing resistors. Using Kirchhoff's voltage law and Ohm's law, the emitter current (I_E) can be derived as I_E = (V_B - V_BE) / R_E, where V_BE (base-emitter voltage) is typically about 0.7V for silicon BJTs. The collector voltage (V_RC) is obtained by applying voltage division principles across the collector resistor. The collector voltage (V_C) and the collector-emitter voltage (V_CE) are then computed by considering the supply voltage and the collector current, taking into account transistor operation modes and load conditions.

Measurement of Circuit Parameters (Part C)

Following the calculations, actual measurements are performed with a digital multimeter or oscilloscope to obtain real-world data. Measuring V_E involves placing the probes across the emitter terminal and ground. I_E is measured indirectly by measuring the voltage across R_E and applying Ohm's law. V_RC is obtained by measuring the voltage across the collector resistor. V_C and V_CE are directly measured at their respective terminals. Accuracy in measurement depends on proper probe placement, device calibration, and eliminating noise that could distort results.

Comparison and Explanation of Differences (Part D)

Comparing the calculated values from Part B with the measured values from Part C reveals the circuit's actual behavior. Differences, if any, can result from tolerances in resistor values, variations in transistor parameters, measurement errors, or temperature effects. For example, the actual V_BE may slightly differ from the typical 0.7V assumed in calculations. Discrepancies help highlight the importance of empirical measurements and understanding real-world components' behaviors versus idealized calculations.

Predictions Based on Changes in V_B (Part E)

If V_B decreases to 0.5 V, a significant reduction from the initial bias voltage, the transistor's base-emitter junction may no longer be forward-biased sufficiently. Consequently, the collector current (I_C) and emitter current (I_E) are expected to decrease. This reduction results in a decrease in voltages across the collector resistor (V_RC), and potentially in V_C and V_CE as well. The emitter voltage V_E might also decrease, reflecting the overall reduction in bias currents. This prediction aligns with the transistor's operation principles, where base bias directly influences collector and emitter currents.

Conclusions from Observations and Measurements (Part F)

Analyzing the measurements and comparing them with theoretical calculations provides insight into the transistor's behavior within the circuit. Observations typically confirm that the actual voltages and currents are close but not identical to calculated values due to component tolerances and environmental factors. The experiment reinforces the understanding that simple models serve as useful approximations, but real-world testing is essential for accurate characterization. Overall, the lab demonstrates the importance of proper biasing, calibration, and measurement techniques in electronic circuit analysis. It highlights how component variations impact circuit performance and underscores the necessity to consider non-ideal factors in practical applications.

References

  • Sedra, A. S., & Smith, K. C. (2018). Microelectronic Circuits (8th ed.). Oxford University Press.
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  • Sedra, A. S., & Smith, K. C. (2021). Microelectronic Circuits (7th ed.). Oxford University Press.
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