What are the EMC challenges of incremental encoders?

The EMC design challenge of incremental encoders lies in their high-frequency pulse signals (up to MHz levels) being sensitive to noise and susceptible to interference over long distances. Specific challenges include:

1) Steep signal edges containing abundant high-frequency components, making them prone to radiation and interference, requiring precise edge control.

2) Strictly maintaining equal length and symmetry in the A/B/Z differential signals is crucial to prevent reduced common-mode rejection.

3) Longer cables present significant impedance matching and terminal reflection issues, potentially causing signal ringing.

4) Encoders are typically coaxially mounted with motors, operating in strong magnetic fields and high-temperature environments.

E-Tech Electronics' solution: Select encoders with output easing, use CML common-mode chokes and ESD protection (ESDSRV05-4H) at the receiving end, and employ 120Ω characteristic impedance twisted-pair shielded cables with proper termination. For high temperatures, automotive-grade components (such as PWRA series inductors) are used.

These measures address the main EMC challenges of incremental encoders in industrial servo systems, enabling stable operation in complex environments.