Table of Contents
- 1 What is the effect of source resistance in an amplifier?
- 2 How does the source and load resistance affect the gain of an amplifier?
- 3 Which amplifier does not have source resistance?
- 4 How is resistance found in a circuit?
- 5 How does the load affect the gain of the CE amplifier?
- 6 How do you determine the resistance of a source?
- 7 What is biasing in BJT amplifier?
- 8 What is the purpose of reand in a BJT circuit?
- 9 Why are there two resistors in a common emitter amplifier?
What is the effect of source resistance in an amplifier?
The source resistance has thermal noise and also converts current noise into voltage noise, increas- ing the amplifier’s total output-voltage noise.
How does the source and load resistance affect the gain of an amplifier?
If the source resistance is increased, the effect will be like a voltage divider reducing the actual voltage at the amplifier input terminals. If the source resistance is increased further the overall gain will be reduced further. The overall gain is reduced.
What is resistance source?
The source resistance of a purely resistive device can be experimentally determined by increasingly loading the device until the voltage across the load (AC or DC) is one half of the open circuit voltage. At this point, the load resistance and internal resistance are equal.
Which amplifier does not have source resistance?
| Q. | If source resistance in an amplifier circuit is zero, then voltage gain (output to input voltage ratio) and source voltage gain (output to source voltage ratio) are the same. |
|---|---|
| A. | true |
| B. | false |
| Answer» a. true | |
| Explanation: when a source resistance rs is present, the voltage gain with respect to source becomes |
How is resistance found in a circuit?
Resistance is a measure of the opposition to current flow in an electrical circuit. Resistance is measured in ohms, symbolized by the Greek letter omega (Ω). Conductors: Materials that offer very little resistance where electrons can move easily.
What is meant by input resistance?
The input resistance is the resistance seen by the current source or voltage source which drives the circuit.
How does the load affect the gain of the CE amplifier?
The voltage gain of a CE amplifier varies with signal frequency. This increases the loading effect of the amplifier stage and serves to reduce the voltage gain. Moreover, at high frequencies, the capacitive reactance of base-emitters junction is low which increases the base current.
How do you determine the resistance of a source?
The source impedance is measured by firstly measuring the open circuit voltage Voc. Then you load the source by a resistance RL which is known. Then measure the the load voltage VL. Then you can calculate RS= ( Voc – VL)/ (VL/ RL).
What happens when internal resistance increases?
High resistance, current is restricted, voltage drops on load; battery heats up. Figure 1: Effects of internal battery resistance. A battery with low internal resistance delivers high current on demand. High resistance causes the battery to heat up and the voltage to drop.
What is biasing in BJT amplifier?
256 ◆BJT Amplifiers 6–1 AmplifierOperATiOn The biasing of a transistor is purely a dc operation. The purpose of biasing is to es- tablish a Q-point about which variations in current and voltage can occur in response to an ac input signal.
What is the purpose of reand in a BJT circuit?
The main benefits of this is that it increases the range of input bias where the circuit operates linearly, makes the circuit gain more stable if the BJT properties vary, and it increases the input resistance of the circuit. If you removed REand replaced it with a wire you’d just have a standard common-emitter amplifier.
Why is there a resistance in the emitter of a BJT?
The resistance in emitter is for stability, because BJTs are highly sensitive in temperature and it will affect your current gain. Having a resistance in emitter will make your circuit more stable than no resistor at emitter.
Why are there two resistors in a common emitter amplifier?
The two resistors have totally different functions. RC is totally fundamental to the operation of a common-emitter amplifier. It determines the voltage gain of the amplifier. If you removed it, you simply wouldn’t have a working circuit, because there’d be no path for current to flow through the collector of the BJT.