GS3140 Datasheet, PDF (12/40 Pages) Semtech Corporation – Multi-Rate Adaptive 3G SDI Equalizer

4. Detailed Description
The GS3140 is a high-speed BiCMOS IC designed to equalize serial digital signals.
The GS3140 can equalize 3G SDI, HD-SDI, SD-SDI and AES10 serial digital signals, and will
typically equalize up to 200m at 2.97Gb/s, 280m at 1.485Gb/s, 500m at 270Mb/s and
200m at 125Mb/s. When DC coupling the output of a device to a 1.2V CML load, the
GS3140 typically consumes 84mW of power with a 400mV_ppd output swing.
4.1 Serial Digital Inputs (SDI/SDI)
The GS3140 has a high-impedance input buffer.
The received serial data signal can be connected to the input pins (SDI/SDI) in either a
differential or single-ended configuration.
The input circuit is self-biasing to allow for simple AC-coupling of input signals to the
device.
4.1.1 Upstream Launch Swing Compensation
The GS3140 has automatic gain control that is based on the assumption that the cable
driver in the upstream device is SMPTE compliant and has a launch swing of
800mV_ppd ± 10%.
When the source amplitude is known to be non-SMPTE compliant, a compensation
adjustment can be made. The GS3140 can adjust for nominal launch swings between
250mV_ppd to 1000mV_ppd, in approximately 50mV_ppd increments. Upstream launch
swing compensation can be adjusted using the LAUNCH_SWING_COMPENSATION bits
in EQ_CONF_REG_2 register. The default value is 800mV_ppd (1011_b).
4.2 Automatic (Adaptive) Cable Equalization
The GS3140 automatically adjusts its gain to equalize and restore signals received over
different lengths of coaxial cable having loss characteristics similar to Belden 8281 or
1694A. The device is designed to automatically equalize SMPTE SDI signal rates up to
2.97Gb/s, DVB-ASI signals at 270Mb/s, and MADI signals at 125Mb/s.
The GS3140 has the ability to limit the reach of the device to one of four values through
its host interface. The default value is the maximum range. The maximum range of the
device is also a function of the detected data rate, so the maximum cable will not exceed
the supported reach for that rate.
GS3140
Final Data Sheet
PDS-060939
Rev.1
May 2015
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