5.8.1 Crosstalk

Crosstalk is noise caused by fast rising or falling signals that couple into the inputs or outputs of the operational amplifier. Frequently, crosstalk occurs from digital signals that are near analog signals. Analog signals with a high input impedance are the most vulnerable to this type of interference.

To minimize crosstalk, keep digital signals as far away from analog inputs and outputs as possible. For high noise signals, such as those from oscillators or clocks, these traces must be kept as short as possible. To minimize noise from the microcontroller, the device must be in sleep and the I/O must not be switched when sensitive operations are on-going. Another way to reduce crosstalk is to reduce the slew rate of the I/O, which reduces the high-frequency components created when switching.

For more information about reducing noise when using the Analog-to-Digital Converter (ADC), consult Microchip Application Note AN4225, “Maximizing the Signal: Tips and Tricks to Properly Acquiring Analog Signals” (DS00004225A).