GS9060 Data Sheet
3.2.2 Carrier Detect Input
For each of the differential inputs, an associated carrier detect input signal is
included, (CD1 and CD2). These signals are generated by Gennum's family of
automatic cable equalizers.
When LOW, CDx indicates that a valid serial digital data stream is being delivered
to the GS9060 by the equalizer. When HIGH, the serial digital input to the device
should be considered invalid. If no equalizer precedes the device, the application
layer should set CD1 and CD2 accordingly.
NOTE: If the GS9064 Automatic Cable Equalizer is used, the MUTE/CD output
signal from that device must be translated to TTL levels before passing to the
GS9060 CDx inputs. See Section 4.1 on page 56 for a recommended transistor
network that will set the correct voltage levels.
A 2x1 input multiplexer is also provided for these signals. The internal
carrier_detect signal is determined by the setting of the IP_SEL pin and is used by
the lock detect block of the GS9060 to determine the lock status of the device,
Section 3.6 on page 28.
3.2.3 Single Input Configuration
If the application requires a single differential input, the second set of inputs may
be left unconnected. Tie the associated carrier detect pin HIGH, and leave the
termination pin unconnected.
3.3 Serial Digital Reclocker
The output of the 2x1 serial digital input multiplexer passes to the GS9060's
internal reclocker stage. The function of this block is to lock to the input data
stream, extract a clean clock, and retime the serial digital data to remove high
frequency jitter.
The reclocker was designed with a 'hexabang' phase and frequency detector. That
is, the PFD used can identify six 'degrees' of phase / frequency misalignment
between the input data stream and the clock signal provided by the VCO, and
correspondingly signal the charge pump to produce six different control voltages.
This results in fast and accurate locking of the PLL to the data stream.
If lock is achieved, the reclocker provides an internal pll_lock signal to the lock
detect block of the device.
22208 - 8 January 2007
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GENNUM [ GENNUM CORPORATION ]
