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= CM-MMCX User Guide: External I/O =

The CM-MMCX clock module routes external clock signals to MMCX connectors. There are four connectors on the module:

||= Connector =||= Signal =||= WARP v3 Connection =||
|| RF Ref Out || RF reference clock output || RF ref clock buffer (U20) CLKOUT0 ||
|| RF Ref In || RF reference clock Input || RF ref clock buffer (U20) CLKIN2 ||
|| Samp Out || Sampling clock output || Sampling clock buffer (U46) CLKOUT1 ||
|| Samp In || Sampling clock Input || Sampling clock buffer (U46) CLKIN2 ||

The frequency of each clock signal will depend on the configuration of the corresponding clock buffer on the host WARP v3 board. Refer to the [wiki:HardwareUsersGuides/WARPv3/Clocking WARP v3 Clocking user guide] for details.

== Connectors ==
The MMCX connectors are standard-polarity, standard-gender 50-ohm MMCX connectors.

The CM-MMCX PCB can be assembled with either MMCX jacks or MMCX plugs, illustrated in the figure below. For connections between WARP v3 kits we recommend CM-MMCX modules with MMCX jacks, which will allow use of readily available cable assemblies with MMCX plugs (like [http://www.digikey.com/product-detail/en/415-0066-024/J731-ND/726044 Digi-Key J731-ND]).

[[Image(wiki:HardwareUsersGuides/CM-MMCX/files:CM-MMCX_versions.jpg)]]