QLX111GRX データシートの表示（PDF） - Intersil

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QLX111GRX

11.1Gb/s Lane Extender

Intersil 

QLx111GRx

FIGURE 6. CML INPUT EQUIVALENT CIRCUIT FOR

THE QLx111GRx

Line Silence/Quiescent Mode

Line silence is commonly broken by the limiting

amplification in other equalizers. This disruption can be

detrimental in many systems that rely on line silence as

part of the protocol. The QLx111GRx contains special

lane management capabilities to detect and preserve

periods of line silence while still providing the

fidelity-enhancing benefits of limiting amplification during

active data transmission. Line silence is detected by

measuring the amplitude of the equalized signal and

comparing that to a threshold set by the voltage at the

DT pin. When the amplitude falls below the threshold,

the output driver stage is muted.

LOS Indicator

Pin LOS is used to output the state of the muting circuitry

to serve as a loss of signal indicator for the device. This

signal is directly derived from the muting signal off the

DT-threshold signal detector output. The LOS signal goes

HIGH when the power signal is below the DT threshold

and LOW when the power goes above the DT threshold.

This feature is meant to be used in optical systems (e.g.

SFP+) where there are no quiescent or electrical-idle

states. In these cases, the DT threshold is used to

determine the sensitivity of the LOS indicator.

Detection Threshold (DT) Pin Functionality

The QLx111GRx is capable of maintaining periods of line

silence by monitoring each channel for loss of signal

(LOS) conditions and subsequently muting the outputs of

a respective channel when such a condition is detected. A

reference voltage applied to the detection threshold (DT)

pin is used to set the LOS threshold of the internal signal

detection circuitry. Voltage control on the DT pin is done

via two external resistors. Both a pull-up and pull-down

resistor are tied to the DT pin, with suggested values

indicated in Figure 8. Other values of the resistors may

also be applicable; therefore customers are advised to

verify DT settings for their specific application.

FIGURE 7. CML OUTPUT EQUIVALENT CIRCUIT FOR

THE QLx111GRx

7

FN6987.0

October 26, 2009

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