I am designing a signal processing circuit from a CT sensor and using an MCU to read the analog signal. I use opamp and other measures to rectify the signal to DC signal and I was able to solve this problem. I wonder if I should add a TVS diode and common mode choke at the input for the purpose of ESD protection and common mode noise filtering because the sensor measures AC current. Will they distort the beneficial signal I am aiming for? Thank you everyone.

 

Are ESD and common mode noise affecting the accuracy of your measurement results? If you have not yet tried building running the circuit, I suggest that you do. Then you can check the accuracy of the measurements to see if they are within the specification limits.

 

If the op-amp input circuitry is designed to ensure that signal levels cannot exceed the op-amp specification (for all likely CT sensor output signal levels) – then filtering (or TVS diodes) that may impact the signal integrity, will not be required.

 

What problem???" and I was able to solve this problem." My mind reading is poor enough that I do not sense what the problem was. But I did eventually see that "CT" was a current transformer.

 

My mind reading skills are excellent – the MCU circuit could only read (sample) positive analogue voltages with reference to 0V; as the CT sensor was outputting an ac signal (which contained negative voltages with reference to 0V), rectifying the signal was one way of solving this.