741 Calle Plano

Camarillo, CA 93012

Tel: 805.388.3700

Fax: 805.388.7565

www.vitesse.com

For more information on Vitesse Products visit the Vitesse web site

at www.vitesse.com or contact Vitesse Sales at (800) VITESSE

or sales@vitesse.com

VSC7997, VSC7998

©2003 Vitesse Semiconductor Corporation

10.7 Gb/s Transimpedance Amplifier

SPECIFICA TIONS:

Single -5.2V Power Supply

2.2mAp-p Input Overload

Operating Temperature: -20C to +100C Junction

Die Size: 1.957 mm x 1.957 mm

The VSC7997 and VSC7998 are 10.7Gb/s high performance transim-pedance

amplifiers designed for use in optical communication networks including Sonet

OC-192/SDH STM-64 and 10G Ethernet fiber links. The devices are intended for

use with a photodetector and are capable of amplifying inputs currents of up to

2.2mA with low duty cycle distortion. The VSC7997 and VSC7998 are pin and

functionally compatible. The designer has the flexibility to choose between the

5KW (VSC7997) and the 1.4KW (VSC7998) differential transimpedance as

required by system architecture and performance.

The VSC7997 and VSC7998 amplifier consists of a transimpedance stage and a

single-to-differential output stage with a gain of 20dB and 11.4dB respectively.

An external photodetector is connected to the IIN input. Pins OUTP and OUTN

are the complementary data outputs. The high gain of the VSC7997 allows for a

direct connection to the VSC8174 CRU/Demux without the need for a post

amplifier.

To provide flexibility in setting the decision threshold of the limiting amplifier or

clock and data recovery circuit, the VSC7997 and VSC7998 utilize output offset

control and adjustment of the OUTP and OUTN. Pins FBIN, OFFP, and OFFN are

used for output offset control. The OFFP and OFFN outputs connected to ground

through 100nF capacitors provide the user with the DC component of the OUTP

and OUTN data outputs. An external circuit can be used to sense the OFFP and

OFFN outputs and then generate the appropriate DC voltage at the FBIN input to

set the DC offset between OUTP and OUTN.

GENERAL DESCRIPTIONS