Four-level gain amplifier

苏澜澜

Four-level gain amplifier [Copy link]

 

I want to make a four-speed gain amplifier. How can I achieve this? If you can help me, I will pay you!

maychang

"I want to make a four-level gain amplifier, how to achieve it?"

For amplifiers made of discrete components (rarely used this way), you can use analog switches to select the appropriate voltage divider ratio on the voltage divider to change the gain. Of course, you can also use mechanical switches, depending on your teacher's requirements.

For amplifiers composed of operational amplifiers, analog switches or mechanical switches can be used to select appropriate voltage divider ratios on the voltage divider to change the gain, and analog switches can also be used to switch feedback resistors to achieve this.

There are ready-made amplifiers on the market that can change gain, which can also be considered a solution, but the price is a bit expensive.

threetigher

Digital potentiometer done!

gmchen

Without specific requirements, it is useless to talk about anything. For questions like this, at least the following should be made clear: gain range, frequency response range. If you are more rigorous, there are also: gain accuracy requirements, input and output signal dynamic range requirements, power supply requirements, etc.

苏澜澜

gmchen posted on 2020-3-12 14:38 Without specific requirements, it is useless to talk about anything. For questions like this, at least the gain range and frequency response range should be made clear. If you are more rigorous, there is also: gain...

Thanks for your advice! I sent it again

苏澜澜

maychang posted on 2020-3-10 11:43 "I want to make a four-speed gain amplifier, how to achieve it" For amplifiers composed of discrete components (rarely used in this way), you can...

I have reposted the requirements, you can go and have a look! Thanks for your advice!

maychang

Su Lanlan posted on 2020-3-13 10:52 I have reposted the request, you can go and have a look! Thanks for your advice!

"I sent it again and asked for something."

Where did it go? The first post has not been modified, and your new post cannot be found in this section.

苏澜澜

maychang posted on 2020-3-13 10:56 "I sent it again with the request or something." Where did it go? The first post has not been modified and edited, and the new post you posted cannot be found in this section...

I just sent it, why is it gone? I'll go look into it.

苏澜澜

maychang posted on 2020-3-13 10:56 "I sent it again with the request or something." Where did it go? The first post has not been modified and edited, and the new post you posted cannot be found in this section...

Still under review, the requirements are as follows

General Purpose Variable Gain Amplifier

1. Mission

Design and manufacture a universal variable gain amplifier, the gain of which can be set manually or program-controlled, without an adjustment potentiometer. The gain variation range, signal input and output range, signal effective frequency band and amplitude-frequency characteristics of the amplifier have high technical and economic indicators.

II. Requirements 1. Basic requirements

(1) The low-frequency and DC maximum undistorted input and output signal amplitudes of the amplifier shall not be less than +3V;

(2) The voltage gain of the amplifier can be set to three levels: 0.10- -1.00, 1.0- -10.0, 10- 100. When the amplifier is in the same level, the gain linearity is not less than 1%, and the resolution is not less than 1%;

(3) When the gain is 100, within the DC-1MHz bandwidth, the output large signal amplitude fluctuation does not exceed 5%;

(4) When the gain is 100 and the input is short-circuited, the output voltage does not exceed +5mV;

(5) The input impedance can be set to greater than 10MW or 50W, and has overvoltage protection capability;

(6) The output impedance of the amplifier can be set to 50W or 0.

2. Play part

(1) The amplifier's low-frequency and DC maximum undistorted input and output signal amplitudes are not less than +8V;

(2) The gain of the amplifier can be set to four levels: 0.100- -1.000, 1.00- -10.00, 10.0- -100.0, 100.0- -1000. When the amplifier is in the same level, the linearity is not less than 0.5% and the resolution is not less than 0.1%;

(3) The gain is 1000, and within the DC-5MHz bandwidth, the output large signal amplitude fluctuation does not exceed 5%;

(4) The output impedance of the amplifier is 50W, the external load is 50W, and in the DC-5MHz frequency band, the waveform distortion is less than 2% when the large signal is output;

(5) When the gain is 1000 and the input is short-circuited, the output voltage does not exceed +20mV;

(6) The overall circuit cost is low and the circuit process is simple; (7) Others. A pc v III. Description

1. The working power supply can be ready-made or homemade.

2. The design report should include the overall system block diagram, the working principle of the variable gain generator, the amplitude, frequency band, gain variation range, device selection method, and main test results. The detailed circuit schematic diagram is provided as an attachment.

maychang

(5) The input impedance can be set to greater than 10MW or 50W, and has overvoltage protection capability;

(6) The output impedance of the amplifier can be set to 50W or 0.

I don't understand. What is 10MW? 10 megawatts? That's power.

maychang

Su Lanlan published on 2020-3-13 11:04 Still under review, the requirements are as follows: Universal variable gain amplifier 1. Task ...

(2) The voltage gain of the amplifier can be set to three levels: 0.10- -1.00, 1.0- -10.0, 10- 100. When the amplifier is in the same level, the gain linearity is not less than 1%, and the resolution is not less than 1%;

Didn’t the first post say that we need the fourth gear?

gmchen

maychang published on 2020-3-13 11:47 (5) The input impedance can be set to greater than 10MW or 50W, and has overvoltage protection capability; (6) The amplifier output...

Obviously it is 10M ohm. Maybe his original document was in WORD format, which has a Symbol font. When he enters W, it displays the capital Greek letter omiga.

gmchen

Su Lanlan published on 2020-3-13 11:04 Still under review, the requirements are as follows: Universal variable gain amplifier 1. Task ...

Judging from your materials, they should be the competition training questions assigned by the teacher, right? The file format is exactly the same as the competition file

gmchen

Su Lanlan published on 2020-3-13 11:04 Still under review, the requirements are as follows: Universal variable gain amplifier 1. Task ...

Let me pick out some nitpicking first.

"When the amplifier is in the same gear, the linearity is not less than 0.5%, and the resolution is not less than 0.1%;", what is linearity? What is resolution?

The guess is: the magnification of each gear is divided into no less than 1000 steps, and the error of the magnification on each step is no more than 0.5% of the maximum magnification of that gear.

If so, then the need for variable gain devices can be calculated. If not, then it is a bit confusing.

In short, there is something wrong with the wording of this requirement in the question.

gmchen

Su Lanlan published on 2020-3-13 11:04 Still under review, the requirements are as follows: General variable gain amplifier 1. Task...

Tell me one more.

"When the gain is 1000 and the input is short-circuited, the output voltage does not exceed +20mV." The +20mV is probably a typo of plus or minus 20mV or a problem in the document format conversion process, and can be ignored.

The question is: Is this 20mV a DC drift voltage or a noise voltage? If we don't figure this out, we can't design it accurately.

It’s still the questioner’s problem.

I have encountered many such questions, which are not rigorous and require others to guess.

gmchen

The requirements of this question are a bit high. I have no problem in answering it, but I don’t know what the questioner meant by “having high technical and economic indicators”? If there are also economic indicators, it’s hard to say.

Black---艾薇

Yes, for sure.