Hi, ADI expert
The figure below shows the serial port design of my MAX3232, The board is connected to the PC through the serial port cable. During the test, I found that there were noise glitches in the phase noise curve of other chip on the board, but after removing cable(at this time, it could not communicate with the PC, the board card could still work normally), there were no noise glitches in the phase noise cureve of the chip.
I think it's the noise that goes from cable to the board, so how do I design the protection circuitry on the MAX3232 to prevent noise from affecting the board's performance?
The picture on the right is trace of rs232_tx signal, PC -> cable-> CON1. The picture on the left is trace of rs232_tx signal, no cable connecting to CON1.
