GS3441 Datasheet, PDF (14/25 Pages) Semtech Corporation – Extended Reach 3G/HD/SD Adaptive Cable Equalizer with Dual Outputs

4. Detailed Description
The GS3441 is a high-speed BiCMOS IC designed to equalize serial digital signals.
The GS3441 can equalize 3Gb/s, HD and SD serial digital signals, and will typically
equalize 210m of Belden 1694A cable at 2.97Gb/s, 300m at 1.485Gb/s and 550m at
270Mb/s. When DC coupling the output of a device to a 1.2V CML load, the GS3441
typically consumes approximately 180mW (one output enabled), 212mW (both outputs
enabled). The GS3441 features dual, independently-controlled outputs, and can be
operated from a single +3.3V DC power supply.
4.1 Serial Digital Inputs
The received serial data signal is connected to the input pins (SDI/SDI) in either a
differential or single-ended configuration. AC-coupling of the inputs is recommended,
because the SDI and SDI inputs are internally biased to approximately 1.87V.
4.2 Automatic (Adaptive) Cable Equalization
The input signal passes through a variable gain equalizing stage, whose frequency
response closely matches the inverse of the cable (Belden 1694A) 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 ensuring that the
correct amount of gain is automatically applied to the input signal for any cable length
within the supported ranges.
The equalized signal is DC-restored, effectively restoring the logic threshold of the
equalized signal to its correct level independent of shifts due to AC-coupling.
4.3 Differential Digital Data Outputs
The digital data output signals have a nominal output voltage swing of either 850mV_ppd
or 425mV_ppd, as set by the OP1_CTL pin for DDO1 and the OP2_CTL pin for DDO2.
Table 4-1 shows the typical output common mode voltage levels related to the two
output swing options and the chosen coupling (DC vs. AC).
Table 4-1: Typical Common Mode Output Voltage Levels
Supply Voltage
(VCC_O)
3.3V
2.5V
1.8V
1.2V
425mV_ppd Swing
425mV_ppd Swing
850mV_ppd Swing
850mV_ppd Swing
(DC-coupled Output) (AC-coupled Output) (DC-coupled Output) (AC-coupled Output)
3.2V
2.4V
1.7V
1.1V
3.1V
2.3V
1.6V
1.0V
3.1V
2.3V
1.6V
1.0V
2.9V
2.1V
1.4V
0.8V
GS3441 Extended Reach 3G/HD/SD Adaptive Cable
Equalizer with Dual Outputs
Final Data Sheet Rev. 1
GENDOC-056647 May 2013
www.semtech.com
14 of 25
Proprietary & Confidential