Selection of RC in power amplifier

lx331lx

Selection of RC in power amplifier [Copy link]

 

I read the specification, which says Gain=2*150K/R. How do I determine the Gain and choose the R, F and C?

If the design uses a 1W amplifier, how do you calculate it?

lx331lx

maychang

lx331lx posted on 2021-4-13 18:01

Gain is the ratio of the output signal amplitude to the input signal amplitude.

What is the amplitude of your input signal? Calculate the gain of your circuit based on the amplitude of your input signal.

lx331lx

maychang posted on 2021-4-13 18:15 Gain is the ratio of the output signal amplitude to the input signal amplitude. What is the amplitude of your input signal? Calculate your circuit based on the input signal amplitude...

That chip doesn't specify the input signal amplitude. . . .

1nnocent

The gain can usually be found in the manual. Take a quick look and then check the manual to see if the gain shown below is what you need.

bqgup

You can use an oscilloscope to test the approximate amplitude of the input signal, and then design the amplification factor to calculate the output. Will the output be distorted? If the input signal amplitude is too large, distortion will also occur. The maximum amplification voltage cannot exceed the power supply voltage.

maychang

lx331lx posted on 2021-4-13 18:49 That chip does not specify the input signal amplitude. . . .

"That chip doesn't specify the input signal amplitude..."

The input signal amplitude is determined by you.

If you don't know the amplitude of your input signal, then as the 6th floor said, test it with an oscilloscope.

lx331lx

maychang posted on 2021-4-13 20:18 "That chip does not specify the input signal amplitude. . . . ." The input signal amplitude is determined by you. If you don't know your input...

So if I determine the value of R by the gain, what value should f take to calculate C?

lx331lx

bqgup posted on 2021-4-13 18:56 You can use an oscilloscope to test the approximate amplitude of the input signal, and then design the amplification factor to calculate the output, whether the output will be distorted, and the input signal...

OK

lx331lx

1nnocent posted on 2021-4-13 18:51 Gains can usually be found in the manual. Take a rough look and then check the manual to see if the following picture is the gain you need

The amplifier has gain, but the chip's input amplitude does not

1nnocent

lx331lx posted on 2021-4-14 09:11 The amplifier has gain, but the chip input amplitude does not

In this case, you know the gain and output load, and you also know the output power you need. You can roughly calculate the input amplitude range by yourself. The input amplitude data sheet will generally indicate it.

maychang

lx331lx posted on 2021-4-14 09:10 If I determine the value of R by the gain, what value should f take to calculate C

After determining the value of R, you also need to know the frequency range of the signal that your amplifier is required to pass. For example, the frequency of a wired telephone is roughly 300 to 3500 Hz, and the frequency of a medium-sized AM radio is roughly 150 to 5000 Hz. The low end frequency of this frequency range is what you call f. This low end frequency is selected by you.

maychang

lx331lx posted on 2021-4-14 09:10 If I determine the value of R by the gain, what value should f take to calculate C

The frequency range is often referred to the speaker in the first post. For a small-diameter speaker (for example, 100mm diameter), even if your amplifier can reach a frequency range of 20 to 20,000 Hz, the speaker cannot reproduce it. Therefore, the amplifier frequency range can be slightly larger than the frequency range that the speaker can reproduce. It is useless if the amplifier can work in a frequency range that is too wide.

1nnocent

1. [I read the specification sheet, which said Gain=2*150K/R. How do I determine the Gain and choose the R?] You all know the formula for gain, which has only two variables, Gain and R. If you determine the Gain according to your needs, then R can be calculated, right?

2. [And the size of F and C] The F and C here should be used for the low-pass filter later. They are all introduced in the manual. If you really don’t know how to calculate, the manual has a schematic diagram. The manual’s description of F is very clear.

3. [If you design a 1W amplifier, how do you calculate it?] You already know the Gain, the load size is determined, and the power size is determined by yourself. Just use P = IR, U/R flexibly. How else can you calculate it? Can't you calculate the input amplitude you asked about by using P = U/R combined with Gain? (If the load size you use is within the range specified in the manual, there will be no big problem with the input range calculated in this way)

lx331lx

maychang posted on 2021-4-14 09:42 After determining the value of R, you also need to know the signal frequency range that your amplifier is required to pass. For example, the frequency of wired telephones is roughly 300-3500Hz, and the frequency of medium...

OK, thank you.

lx331lx

1nnocent posted on 2021-4-14 09:49 1. [I read the specification book, which says Gain=2*150K/R. How do I determine the size of Gain and choose the size of R?] Your gain is...

The C I'm talking about is the one for input...