Help - Amplifier Frequency Voltage relationship

In summary, the output voltage drops away in an amplifier when the frequency is above or below the bandwidth due to the capacitance effect. This is because the capacitance impedance decreases as the frequency increases, causing the gain of the amplifier to fall to zero. The explanation for this is that the components of the amplifier have capacitance, which takes time to charge and discharge, causing the amplifier to not be able to keep up with high-frequency input. Additionally, inductance also plays a role in some amplifiers.
  • #1
Simon M
3
0
Can someone help me by describing why the output voltage drops away in an amplifier when the frequency is above or below the bandwidth?
 
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  • #2
The easist explanation is that the components of the amplifier have capacitance, and that capacitance takes time to charge and discharge. Essentially, the amplifier is not able to swing its output fast enough to keep up with a high-frequency input.

- Warren
 
  • #3
The in-depth explanation is that if you do an impedance analysis of the amplifier, and get the frequency response plot of the amplifier, you have the answer to your question. In amplifiers, there is always the capacitance effect, and capacitance impedance drops as the frequency of the input signal increases. (NB: Z=1/jwC where w=angular frequency of the signal) So the gain of the amplifier in the frequnecy response plot will fall to zero as w increases. The physical explanation of why the capacitance drops as frequency increases has been explained by chroot.
 
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  • #4
Don't forget inductance. It plays a large part in some amplifiers.
 
  • #5
Hey...Thanks.

It was clear that impedance is a main contributing factor that effects voltage output but I was unsure about the relationship between frequency and impedance. Got it now!
 

1. What is the relationship between amplifier frequency and voltage?

The relationship between amplifier frequency and voltage is often described as an inverse relationship. This means that as the frequency of the amplifier increases, the voltage will decrease and vice versa. This relationship is determined by the amplifier's gain, which is the measure of the output voltage compared to the input voltage.

2. How does amplifier frequency affect the overall performance of a circuit?

The frequency response of an amplifier is a crucial factor in determining its performance. A wider frequency response means that the amplifier can handle a wider range of frequencies, resulting in a more accurate and efficient amplification of the signal. On the other hand, a limited frequency response can result in distortion and loss of signal quality.

3. Can the amplifier frequency and voltage relationship be changed?

Yes, the relationship between amplifier frequency and voltage can be changed by adjusting the amplifier's gain. By increasing or decreasing the gain, the frequency and voltage relationship can be altered. However, this can also affect other aspects of the amplifier's performance, so it should be done carefully.

4. What is the importance of understanding the amplifier frequency and voltage relationship?

Understanding the amplifier frequency and voltage relationship is crucial for designing and troubleshooting circuits. It allows engineers to select the appropriate amplifier for a specific frequency range and ensure that the signal is amplified accurately and efficiently. It also helps in identifying and resolving any issues that may arise in the circuit.

5. Is there a specific formula to calculate the amplifier frequency and voltage relationship?

There is no specific formula to calculate the relationship between amplifier frequency and voltage. It is dependent on the amplifier's gain and the input and output signals. However, the frequency response curve of an amplifier can provide a visual representation of this relationship and can be used to determine the amplifier's performance at different frequencies.

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