Clock Input Impedance
The termination impedance provided by the clock’s reference input, including any selectable options.
Input termination describes the electrical load at the receiving connection. It is separate from output impedance, signal voltage and the impedance of a recommended cable.
Clock Input Impedance — External Clock
For an External Clock, input impedance matters when connecting another timing reference to it. The selected termination should follow the requirements of the sending device and the intended connection arrangement.
Values may include 50 Ω, 75 Ω or high impedance. A switch that disables a 75 Ω termination provides a high-impedance option as well as 75 Ω. Read the specification for the input itself; a BNC connector alone does not establish its impedance.
Compare the available setting with the source, cable and termination instructions for the complete link. High impedance is an operating option, not a superior quality rating. Correct impedance alone does not establish compatibility: the accepted frequency, waveform and input level must also match the reference signal.