This optional upgrade allows ATS9440 to perform analog to digital conversion based on an external clock signal. There are three supported types of External Clock:
Fast External Clock
A new sample is taken by the on-board ADCs for each rising edge of this External Clock signal. Fast External Clock frequency must always be higher than 1 MHz and lower than 125 MHz in order to satisfy the clocking requirements of the ADC chips being used.
Slow External Clock
This type of clock should be used when the clock frequency is either too slow or is a burst-type clock. In this mode, the ATS9440 ADCs are run at a preset internal clock frequency. The user-supplied Slow External Clock signal is then monitored for low-to-high transitions. Each time there is such a transition, a new sample is stored into the onboard memory.
10 MHz Reference Clock
It is possible to generate the sampling clock based on an external 10 MHz reference input. ATS9440 uses an on-board low-jitter VCO to generate the 125 MHz or 100 MHz high frequency clock used by the ADC. This sampling clock can then be decimated by any integer factor, e.g. 2, 3, 4...
ATS9440 External Clock Upgrade allows you to supply the ADC clock. This option is extremely important in many RF applications in which phase measurements must be made between the inputs themselves or between the inputs and an external event. One of the supported External Clock modes is 10 MHz Reference Clock mode, which is useful for RF systems that use a common 10 MHz reference clock. The Fast External Clock mode is the ideal clocking scheme for OCT applications.