GS3441 Extended Reach 3G/HD/SD Adaptive Cable

Equalizer with Dual Outputs

Final Data Sheet

Rev. 1

GENDOC-056647

May 2013

14 of 25

Proprietary & Confidential

www.semtech.com

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

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)

(DC-coupled Output)

(AC-coupled Output)

(DC-coupled Output)

(AC-coupled Output)

3.3V

3.2V

3.1V

3.1V

2.9V

2.5V

2.4V

2.3V

2.3V

2.1V

1.8V

1.7V

1.6V

1.6V

1.4V

1.2V

1.1V

1.0V

1.0V

0.8V