Subject: TRONLA 2 Name: RABAYA, Janray S. Section: ECE-3A n: 25

Design Exercise 43DC Loadline for a BJT Amplifier

Journal:

In this laboratory activity, we performed on how to make a Fixed Bias configuration of a Bipolar Junction Transistor (BJT). The circuit is also called as a "Base Current Bias", the fact that the transistors base current, IB stays consistent for given values of Vcc, and in this manner the transistors operating point should likewise remain fixed. This type of transistor biasing arrangement is also beta dependent biasing as the steady-state condition of operation is a function of the transistor’s beta β value, so the biasing point will vary. With this type of biasing method the voltages and currents do not remain stable during transistor operation and can vary enormously. Also the temperature of the transistor can affect the operating point.

I almost lose my patience in this activity because of trials and errors I made yet still have a high percentage error. It is true that if you have a high value of “n” you may never find a solution to lower your error. The dirty lab is like a trap hole, since temperature affects the transistor, I already thought I made a design that could satisfy me. When I got to check my design into the other room which have a cool temperature inside, everything changed and got my work became useless at all. No found solution yet and I’m hoping that this “n” will not be curse for me.

In conclusion, this activity was an incredible approach to test the most fundamental arrangement of a Bipolar Junction Transistor (BJT). With a fundamental setup, for example, this one, we could control the resistor values we required keeping in mind the end goal to accomplish our required targets. What's more, I propose that in applying a BJT in a circuit I recommend the voltage-divider design, on the facts that we have learned amid our TRONIC1 and TRONLA1 last semester this kind of setup is free on Beta β so a wide change on it due to the temperature of the transistor wouldn't influence the output current that much.

Subject: TRONLA 2 Name: RABAYA, Janray S. Section: ECE-3A n: 25

Design Exercise 43DC Loadline for a BJT Amplifier

Question and Answer:

What is the most widely used combination-bias system?

A. Emitter BiasB. Fixed BiasC. Voltage Divide BiasD. Emitter Follower

Background: This biasing configuration comes from the fact that the two resistors RB1 and RB2 form a

voltage or potential divider network with their center point connecting the transistors base terminal directly across the supply. Also, voltage divider network biasing makes the transistor circuit independent of changes in beta as the voltages at the transistors base, emitter, and collector are dependent on external circuit values. The current flowing through resistor RB2 is generally set at 10 times the value of the required base current IB so that it has no effect on the voltage divider current or changes in Beta.

Reference: 1. Electronic Devices and Circuit Theory by Robert L. Boylestad2. https://en.wikipedia.org/wiki/

Bipolar_transistor_biasing#Fixed_bias_with_emitter_resistor

Answer: C