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Reference
3-16 GB1400 User Manual
Single-ended or Differential Operation
DATA-BAR and CLOCK-BAR are complimentary outputs to DATA and
CLOCK respectively. Therefore, to drive a single-ended clock or data input
simply connect appropriate true output (CLOCK or DATA) while terminating its
compliment (CLOCK-BAR or DATA-BAR) with 50 Ohms to ground. Or, to
drive a differential clock or data input, connect the appropriate true output
(CLOCK or DATA) to the non-inverting input and the complimentary output
(CLOCK-BAR or DATA-BAR) to the inverting input. No other setup is required
to configure the Generator for singled-ended or differential operation.
Procedure for Single-ended Operation (TX only)
1. For singled-ended operation, connect Generator CLOCK and DATA outputs
to singled-ended inputs on the DUT.
2. Terminate the CLOCK-BAR and DATA-BAR outputs with 50 Ohms to
ground.
Procedure for Differential Operation (TX only)
1. Connect CLOCK and CLOCK-BAR outputs of the Generator to the true and
complimentary clock inputs on the DUT.
2. Connect DATA and DATA-BAR outputs of the Generator to the true and
complimentary data inputs on the DUT.
Pattern Sync and CLOCK/4 Outputs
The OUTPUT section of the Generator front panel contains two additional
outputs that may be useful when observing the Generator output with an
oscilloscope. The first is the Pattern Sync or output which generates one pulse
per pattern frame. This signal may be used to trigger an oscilloscope at the
beginning of the output data pattern. The second is the CLOCK/4 output, which
is a clock signal at one quarter the frequency of CLOCK. This signal is
particularly useful when viewing the output of the Generator using an
oscilloscope that doesn't have sufficient bandwidth to trigger on the CLOCK
signal.
Both the Pattern Sync and CLOCK/4 outputs have a fixed amplitude of 200 mV
pk-pk, centered around ground, when terminated by 50 Ohms to ground. The
phase relationship of CLOCK/4 and CLOCK is also fixed, with the nominal
location of CLOCK/4 transitions occurring on the falling edge of CLOCK.
The width and location of the Pattern Sync pulse depends on which pattern type
is currently active. For PRBS patterns, the Pattern Sync pulse has a width equal
to one bit time slot, at a fixed position not adjustable by the user. For short-
WORD patterns (1-Mbit Option not installed) the Pattern Sync waveform is a
nominal square wave that is high during the first byte of a 16-bit WORD, and
low for the second. For long-WORD patterns (1-Mbit Option installed), the
Pattern Sync pulse is one byte wide that occurs at the beginning of the frame.