How to suppress the output noise of the I/O module AO?

Suppressing noise at the analog output of I/O modules requires end-to-end control, from the DAC chip and output buffer to routing. First, provide the DAC chip with an extremely clean reference voltage and power supply, typically using a low-noise LDO and multi-stage LC filtering. At the DAC output, use a low-noise, low-bias-current operational amplifier as a buffer, and its power supply must be adequately decoupled. A simple RC low-pass filter can be added at the op-amp output, with a cutoff frequency slightly higher than the signal bandwidth, to filter out high-frequency noise generated by the op-amp itself and digital coupling.

During routing, analog output traces must be kept away from digital and power lines and grounded. If a current-output DAC is used, its output loop area should be minimized. At the system level, use separate shielded cables for the AO channels, and connect the shielding to a clean analog ground at the module end. For low-frequency noise that cannot be filtered out, its source can be traced; for example, it may be power supply ripple or digital ground noise coupled through a common ground impedance, requiring targeted isolation or filtering. Measuring output noise with a high-resolution oscilloscope or spectrum analyzer can pinpoint the problem precisely.