GS2975A Datasheet, PDF (16/27 Pages) Gennum Corporation – HD-LINX® III Multi-Rate SDI Automatic Reclocker with Dual Differential Outputs

4. Detailed Description
The GS2975A is a Multi-Rate Serial Digital Reclocker designed to automatically recover
the embedded clock from a digital video signal and re-time the incoming video data.
The GS2975A will recover the embedded clock signal and re-time the data from a
SMPTE 424M, SMPTE 292M, or SMPTE 259M-C compliant digital video signal.
Using the functional block diagram (page 2) as a guide, Slew Rate Phase Lock Loop
(S-PLL) on page 16 to on page 21 describes each aspect of the GS2975A in detail.
4.1 Slew Rate Phase Lock Loop (S-PLL)
The term “slew” refers to the output phase of the PLL in response to a step change at the
input. Linear PLLs have an output phase response characterized by an exponential
response whereas an S-PLL’s output is a ramp response (see Figure 4-1). Because of this
non-linear response characteristic, traditional small signal analysis is not possible with
an S-PLL.
0.2
INPUT
0.1
OUTPUT
0.0
SLEW PLL RESPONSE
0.2
INPUT
0.1
OUTPUT
0.0
LINEAR (CONVENTIONAL) PLL RESPONSE
Figure 4-1: PLL Characteristics
GS2975A HD-LINX® III Multi-Rate SDI Automatic
Reclocker with Dual Differential Outputs
Data Sheet
41487 - 4
April 2009
16 of 27