Circuit help, how do you analyze this circuit?

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Circuit help, how do you analyze this circuit? [Copy link]

 

Circuit help, how to analyze this circuit? The channel is DC

我是三零

Richard-LXQ

I am Sanling, published on 2021-9-18 15:38

Your circuit is not complete. There is negative voltage but no positive voltage?

呜呼哀哉

I am Sanling, published on 2021-9-18 15:38

Determine whether the left side of R212 is connected to the non-inverting terminal of the op amp.

U8A, C80, R213, R214, and C83 form an isolation resistor plus a double-feedback capacitive load stabilization circuit.

The problem is that your output returns to the non-inverting terminal through R215 and R212.

Richard-LXQ

SOP8, only half

我是三零

Alas, published on 2021-9-18 16:00 Make sure the left side of R212 is connected to the in-phase terminal of the op amp. U8A, C80, R213, R214, C83 are composed of an isolation resistor plus a double feedback capacitor negative...

Make sure it is connected to the positive terminal

This circuit is the output stage of a DC bias voltage generating circuit, in order to output a DC voltage of about 30V

我是三零

Richard-LXQ posted on 2021-9-18 16:01 SOP8, only half

The other half is just in the front stage, +18V power supply

maychang

I am Sanling, published on 2021-9-18 15:38

This circuit may be wrong and incomplete.

Since one end of C76C77 is grounded, the other end may be the positive end of the power supply. However, there is only a 20 ohm resistor (R215R214) from the positive end of the power supply to the output of the op amp, which is almost impossible.

我是三零

maychang posted on 2021-9-18 16:59 This circuit may be wrong and incomplete. From the grounding of one end of C76C77, the other end may be the positive end of the power supply. However, there is only 20 ohms from the positive end of the power supply to the output of the op amp...

I feel the same way. I analyzed it several times.

But the board is made and the measured value is correct

The circuit is inherited from the past

People are already stupid

maychang

I am Sanling and published on 2021-9-18 16:10 The circuit connected to the forward end is the output stage of a DC bias voltage generating circuit, in order to output a DC voltage of about 30V...

"In order to output a DC voltage of about 30V"

The power supply voltage is plus or minus 18V, so it is impossible to output a DC voltage of around 30V.

whuer

This is a voltage follower, in order to drive a large capacitor

wenyangzeng

Sine wave generator only

埋土书生

This circuit appears to be a current amplifier, which amplifies the input current by twice to the output, and this function is accomplished by R212 and R215.

If you know the specific purpose of the circuit, it will be better analyzed