Keysight Technologies N5171B EXG, Руководство пользователя

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Keysight EXG and MXG X-Series Signal Generators User’s Guide 295
Digital Signal Interface Module (Option 003/004)
Clock Timing
Figure 10-6 Clock Timing for a Serial Port Configuration
Clock Timing for Phase and Skew Adjustments
The N5102A module provides phase and skew adjustments for the clock relative to the data and
can be used to align the clock with the valid portion of the data. The phase has a 90 degree
resolution (0, 90, 180, and 270 degree selections) for clock rates from 10 to 200 MHz and a 180
degree resolution (0 and 180 degree selections) for clock rates below 10 MHz and greater than 200
MHz.
The skew is displayed in nanoseconds with a maximum range of ±5 ns using a maximum of ±127
discrete steps. Both the skew range and the number of discrete steps are variable with a
dependency on the clock rate. The skew range decreases as the clock rate is increased and
increases as the clock rate is decreased. The maximum skew range is reached at a clock rate of
approximately 99 MHz and is maintained down to a clock rate of 25 MHz. For clock rates below 25
MHz, the skew adjustment is unavailable.
A discrete step is calculated using the following formula:
The number of discrete steps required to reach the maximum skew range decreases at lower
frequencies. For example, at a clock rate of 50 MHz, 127 steps would exceed the maximum skew
range of ±5 ns, so the actual number of discrete steps would be less than 127.
Figure 10-7 is an example of a phase and skew adjustment and shows the original clock and its
phase position relative to the data after each adjustment. Notice that the skew adjustment adds to
the phase setting.
Clock
4 bits per word
1 Sample
Frame Marker
Data Bits
1
256 Clock Rate
×
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