
12
Error add input (ERROR ADD)
The external error add input adds a single error to the data output
for each rising edge at the input. When electrical idle is selected
for the data and aux data outputs: a logical high state causes
the output to transition to electrical idle state. A logic low state
causes the outputs to return to normal operation.
Table 6. Specifications for error inject input
Levels TTL compatible
Interface DC coupled, 50 Ω nominal
Connector SMA female
10 MHz reference output (10 MHZ REF OUT)
Table 7. Specifications for the 10 MHz reference output
Amplitude 1 V into 50 Ω typical
Interface AC coupled,
50 output impedance
Connector BNC, rear panel
Specifications-Pattern Generator
Table 8. Specifications for trigger/reference clock output
Pulse width Square wave
Amplitude/ resolution 0.050 V to 1.800 V, 5 mV steps.
Addresses LVDS, CML, PECL, ECL
(terminated to 1.3V/0 V/-2 V), low
voltage CMOS
Output voltage window - 2.0 V to +3.0 V
Predefined levels ECL, PECL (3.3V), LVDS, CML
Transition times < 20 ps typical (20% to 80%)
< 25 ps typical (10% to 90%)
Interface
1
DC coupled, 50 Ω nominal,
Single ended or differential
Connector 2.4 mm female
1. Unused output must be terminated with 50 Ω to GND.
AUX input (AUX IN)
When the alternate pattern mode is activated, the memory is split
into two parts, and the user can define a pattern for each part.
Depending on the operating mode of the auxiliary input, the user
can switch the active pattern in real time by applying a pulse
(mode 1) or a logical state (mode 2) to the auxiliary input. If the
alternate pattern mode is not activated, the user can suppress the
data on the data output by applying a logical high to the auxiliary
input (mode 3).
Table 9. Specifications for auxilliary input
Levels TTL compatible
Interface DC coupled, 50 Ω nominal
Connector SMA female
Trigger/reference clock outputs
(TRIGGER/ REF CLK OUT)
This output provides a trigger signal synchronous with the
pattern, for use with an oscilloscope or other test equipment.
Typically there is a delay of 32 ns between trigger and data output
for data rates > 620 Mb/s. The trigger output has two modes.
Pattern trigger mode: For PRBS patterns; the pulse is synchro-
nized with a user specified trigger pattern. One pulse is generated
for every 4th PRBS pattern.
Divided clock mode: Generates a square wave (clock) with the
frequency of the full-rate clock divided by 2, 4, 8, 10, 16, 20, 24,
25, 26, up to 32,792 . It is possible to enable/disable SJ, SSC or
residual SSC for this output to use it as a lower frequency
reference clock.
Auxillary clock output (AUX CLK OUT)
This output is intended as clock input for N4916B de-emphasis
signal converter and the 28 Gb/s 2:1 multiplexer N4876A.
Table 10. Specifications for auxillary clock output
Output level > 150 mV typical
Clock signal Full-rate
Interface AC coupled, 50 nominal
Connector SMA female
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