GS2964 Datasheet, PDF (10/17 Pages) Gennum Corporation – SMPTE 424M, SMPTE 292M and SMPTE 259M compliant

4. Detailed Description
The GS2964 is a high-speed BiCMOS IC designed to equalize serial digital signals.
The GS2964 can equalize 3Gb/s, HD and SD serial digital signals, and will typically
equalize 100m of Belden 1694A cable at 2.97Gb/s, 140m at 1.485Gb/s and 180m at
270Mb/s.The GS2964 is powered from a single +3.3V power supply and consumes
approximately 215mW of power.
4.1 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.
4.2 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.
4.3 Serial Digital Outputs
The digital output signals have a nominal voltage of 800mV_pp differential, or 400mV_pp
single-ended when terminated with 50Ω as shown in Figure 4-1.
GS2964 Adaptive Cable Equalizer
Data Sheet
51913 - 3
March 2010
10 of 17