GS2961 Datasheet, PDF (29/104 Pages) Gennum Corporation – 3Gb/s, HD, SD SDI Receiver, with Integrated Adaptive Cable Equalizer complete with SMPTE Video Processing

The GS2961 distinguishes between Level A and Level B mappings at 3Gb/s. When Level
B data is detected, each 10-bit link is demultiplexed into its individual component
streams, and most video processing features, including error detection and correction
are enabled separately for Data Stream 1 and Data Stream 2 (Link A and Link B,
respectively). Note that ancillary data extraction can only be enabled for one link for
3Gb/s Level B data. Data Stream 1 or Data Stream 2 can be selected via the host interface.
4.3 Serial Digital Input
The GS2961 can accept serial digital inputs compliant with SMPTE 424M, SMPTE 292
and SMPTE 259M-C.
4.3.1 Integrated Adaptive Cable Equalizer
The GS2961 integrates Gennum's adaptive cable equalizer technology.
The integrated adaptive equalizer can equalize 3Gb/s, HD and SD serial digital signals,
and will typically equalize 150m of Belden 1694A cable at 2.97Gb/s, 250m at 1.485Gb/s
and 480m at 270Mb/s.The integrated adaptive equalizer is powered from a single +3.3V
power supply and consumes approximately 195mW of power.
The equalizer can be bypassed by programming register 073h through the GSPI
interface.
4.3.1.1 Serial Digital Inputs
The Serial Data Signal may be connected to the input pins (SDI/SDI) in either a
differential or single ended configuration. AC coupling of the inputs is recommended, as
the SDI and SDI inputs are internally biased at approximately 1.8V.
4.3.1.2 Cable Equalization
The input signal passes through a variable gain equalizing stage whose frequency
response closely matches the inverse of the cable loss characteristic. In addition, the
variation of the frequency response with control voltage imitates the variation of the
inverse cable loss characteristic with cable length.
The edge energy of the equalized signal is monitored by a detector circuit which
produces an error signal corresponding to the difference between the desired edge
energy and the actual edge energy. This error signal is integrated by both an internal and
an external AGC filter capacitor providing a steady control voltage for the gain stage. As
the frequency response of the gain stage is automatically varied by the application of
negative feedback, the edge energy of the equalized signal is kept at a constant level
which is representative of the original edge energy at the transmitter. The equalized
signal is also DC restored, effectively restoring the logic threshold of the equalized signal
to its correct level independent of shifts due to AC coupling.
GS2961 3Gb/s, HD, SD SDI Receiver, with Integrated
Adaptive Cable Equalizer
Data Sheet
48004 - 2
November 2009
29 of 104