NF WAVE FACTORY WF1967, Instruction Manual (Operations

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4.4 Setting for Main Items
WF1967/WF1968
4-45
c) Difference between standard and enhanced duty variable range
Variable range Features
Standard
Setting range: 0.0100% to 99.9900%
• Duty can be changed within the range where jitter is low and the
pulse does not disappear.
• The setting range of the duty narrows as the frequency rises.
• The duty is fixed at 50% at 70MHz.
Enhanced
Setting range: 0.0000% to 100.0000% (independent of frequency)
• There is jitter of 700ps rms or lower typ., and the duty can be
always changed from 0% to 100%.
• The pulse might sometimes disappear when the pulse width of the
high level or the low level is narrower than that of 2.4ns. However,
it becomes equal to the specified duty on average.
• When 0% is set, the waveform is fixed to the low level, and when
100% is set, the waveform is fixed to the high level. The pulse is
not output in either case.
• When the oscillation frequency is an integer ratio compared to
420MHz, the edge time will become indeterminate by
approximately 2.3ns. Under other conditions, it will be the
specified duty "on average".
d) Restriction of duty and frequency when duty variable range is standard
The setting range of the duty is limited by the frequency within the following ranges:
For example, the variable range at 14MHz is limited to the range from 10% to 90%.
If the above-mentioned restriction is not filled by setting the frequency, the duty is adjusted.
Frequency (Hz)/1 400 000
≦
Duty (%)
≦
100 - Frequency (Hz)/1 400 000
Check
When the duty variable range is enhanced, the frequency might become
lower than the setting, because the pulse may disappear depending on the
setting. Do not use it for the usage in which the frequency should be kept
constant.