When using crystal oscillators with an HCMOS compatible output signal, impedance mismatches may occur. It happens, when a low source impedance output is used to drive a PCB trace with a higher impedance. This can cause noise in the clock signal. Therefore, matching the impedance between the oscillator output and the transmission line is recommended for HCMOS circuits.
This document describes the challenge with HCMOS crystal oscillators and shows possible configuration approaches to ensure interference-free clock signals.
Here's what you can expect:
