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M2i.30xx / M2i.30xx-exp Manual
Overview
Clock generation
Clock generation
Overview
The different clock modes
The Spectrum M2i cards offer a wide variety of different
clock modes to match all the customers needs. All of the
clock modes are described in detail with programming ex-
amples in this chapter.
The figure is showing an overview of the complete engine
used on all M2i cards for clock generation.
The purpose of this chapter is to give you a guide to the
best matching clock settings for your specific application
and needs.
Standard internal sample rate (PLL)
PLL with internal 10 MHz reference. This is the easiest and most common way to generate a sample rate with no need for additional external
clock signals. The sample rate has a fine resolution. You can find details on the granularity of the clock in PLL mode in the technical data
section of this manual.
Quartz1 with or without divider
This mode provides an internal sampling quartz clock with a dedicated divider. It’s best suited for applications that need an even lower clock
jitter than the PLL produces. The possible sample rates are restricted to the values of the divider. For details on the available divider values
please see the according section in this chapter or take a look at the technical data section of this manual.
Quartz2 with or without PLL and/or with or without divider (optional)
This optional second Quartz2 is for special customer needs, either for a special direct sampling clock or as a very precise reference for the
PLL. Please feel free to contact Spectrum for your special needs.
External reference clock
PLL with external 1 MHz to 125 MHz reference clock. This provides a very good clock accuracy if a stable external reference clock is used.
It also allows the easy synchronization with an external source.
Direct external clock
Any clock can be fed in that matches the specification of the board. The external clock signal can be used to synchronize the board on a
system clock or to feed in an exact matching sample rate.
Direct external clock is not available for M2i.49xx cards. Please use external reference clock mode instead.
External clock with divider
In addition to the direct external clocking it is also possible to use the externally fed in clock and divide it for generating a low-jitter sample
rate of a slower speed than the external clock available.
Direct external clock with divider is not available for M2i.49xx cards. Please use external reference clock
mode instead.
Synchronization clock (optional)
The star-hub option allows the synchronization of up to 16 cards of the M2i series from Spectrum with a minimal phase delay between the
different cards. As this clock is also available at the dividers input, cards of the same or slower sampling speeds can be synchronized. For
details on the synchronization option please take a look at the dedicated chapter in this manual.
