How to interface 3.3V CML to an HCSL receiver for IDT timing devices

AC coupling a 3.3V CML  to an HCSL receiver with or without internal termination can be accomplished using a small number of passive components. Figure 1 shows an example of CML drive to HSCL input interface. In this example, the HCSL receiver is high input impedance, i.e. there is no buit-in termination. The CML driver is has no built-in 50 ohm pull up resistors. If the CML has built-in pull up resistor, there is no need to install the R1 and R2. Figure 2 and Figure 3 show interface circuit other possible types of built-in termination in the receivers. See the solutions below. For other questions not addressed by the Knowledge Base, please submit a technical support request.