Specifications
32
GTS1063 and GTS1250 GBIC Test Systems Instruction Manual
Table 8: External Clock Input Specifications (cont.)
Specification
Description
Input clock rate
GTS1250:
1.250000 GHz
"
1%
GTS1063:
1.062500 GHz
"
1%
These rates are the limits of the External Clock Input to receive externally supplied NRZ
Data (within level specifications with the longest consecutive pattern of 1s and 0s not
more than seven) and to then pass this serial data as a differential 75
signal into the
GBIC receTX_DATA and –Tx_DATA signal paths without significant RC time
constants being imposed on the data sequence.
Jitter Transfer and tolerance
Horizontal jitter transfer: 1:1
Jitter tolerance: not specified
The EXT CLK IN clock is divided by 10 and drives a parallel 10-bit-to-serial serializer-
deserializer (SERDES) IC to produce the serial data stream; this serial data stream is
retimed against the full serial clock, and as such the outgoing data will have the same
timing jitter content as the EXT CLK IN signal.
Table 9: External Tx Jitter Input Specifications
Specification
Description
Input-to-DATA jitter transfer function
A 1 V input yields approxi110 ps increase in logic HIGH pulse widths: (500 mV
pp
maximum input). Values exceeding
"
500 mV and less than 2.0 V typically yield 130 ps
per Volt.
The Tx Jitter Input signal is DC coupled, divided by 5, and applied added to the V
bb
logic
threshold of one side of a differential digital ECL gate in series with the serial 1.25 Gb/s
Tx DATA path. This coupling allows the external DC signal to directly modulate the digital
DATA threshold, in effect causing both positive and negative fluctuations in the duty cycle
(pulse width) of the serial DATA stream. The rising edge of the internally generated DATA
signal is not strictly specified, and therefore the transfer function of the externally supplied
Tx Jitter to horizontal timing jitter is subject to variations. In general, however, small
signals input as jitter (
t
500 mV
pp
) will be more linear than large signals.
Input bandwidth, typical
–3 dB bandwidth: DC to 4.75 MHz (
"
0.5 MHz)
The frequency at which the peak-to-peak pulse width edge variation is –3 dB (0.707) of
that experienced at frequencies approaching DC.
Maximum nondestructive voltage input
(AC or DC)
5 Volts
This is the maximum nondestructive DC potential that can be applied to this input; the
input 50
termination can be damaged above this level.
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