Input (1000 mv)+amplification (48dB, 6dB step size)+bandpass (100 ~ 50k Hz)+ program-controlled lowpass (1KHz ~ 25 kHz variable, step size 1KHz, 2fc attenuation 8dB).

I wonder if the above is what you need?

If the bandpass is 48dB and 2fc is less than 40dB, it should be attenuated by 8dB. Is that so?

(Isn't this requirement too simple, only a second-order all-pole filter is needed to realize it? )

If you understand it as above, then you are not very difficult.

1, program-controlled amplification can be realized in two ways.

1. 1 6dB=2 times, 12dB=4 times, 18dB=8 times, 24dB= 16 times, 36dB, 42dB, 48dB.

It can be realized by two-stage MAX5426, and the first stage adopts 2 times fixed amplification.

take for example

6dB

The first stage =2, the second stage = 1, the third stage = 1, and the total magnification =2.

12db

The first stage =2, the second stage =2, the third stage = 1 and the total amplification =4.

etc

1.2 multiplication directly with analog multiplier (simple)

1.3 adopts 8 analog switches to select (the method is the simplest and the lowest cost, but the performance is the worst, so it is difficult to achieve accurate setting).

2, low-pass filter, relatively simple, there are many switched capacitor programmable filters on MAXIM.

You can completely achieve your 10%, such as MAX260, 262, 26 1, etc. , and adjust the low-pass cutoff frequency setting by inputting the frequency.

3, parameter display, I don't know what you mean, can you understand a LCD display?

What are the amplification settings and low-pass settings of your amplifier? This is much simpler.

Since the program control should be controlled by MCU or other single chip microcomputer processing IC, then design one.

The screen of 12864 is ok.

I can only give you some reference suggestions, and you need to do it yourself.

Others can only guide you to finish it, not design it for you.

Scheme drawings:

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