Receiving at high speed

Agere Systems has extended its range of high speed receivers for 10Gbit/sec transmission.

The new single-ended receivers – part of the Agere R2860 family – include a 10 Gbit/s avalanche photo-detector (APD) receiver, a 10 Gbit/s positive-intrinsic-negative (PIN) receiver with integrated limiting amplifier, and a 12.5 Gbit/s PIN receiver which enables super forward-error correction (FEC).

These R2860 devices complement Agere’s existing R192-series of 10 Gbit/s differential output receivers, and can be used in 10 Gbit/s short, intermediate and long-haul applications.

‘These receivers are available in multiple configurations, giving systems makers the options they need in designing multi-channel dense wavelength division multiplexing systems and single-channel SONET/SDH systems,’ explained Ramzi Sawires, senior marketing manager for Agere’s Access division.

‘In addition, all of the R2860 family of receivers feature identical packaging characteristics, making it easier for manufacturers to drop-in whichever receiver best meets their requirements.’

Agere’s RA2860D APD receiver offers a 26 dBm dynamic range, -26 dBm sensitivity and zero dBm overload.

APD receivers provide higher sensitivity than PIN-based receivers by using internal ‘avalanche’ multiplication of light-generated electrons.

Better sensitivity translates to lower demands on the transmission side and longer transmission distances. Overload measures how susceptible a receiver is to saturation due to optical input power.

‘Our APD receiver’s high sensitivity can help systems makers save on costs by using lower-power lasers or increasing the distance between amplified spans in an optical network,’ Sawires said.

The RA2860D is a 1R receiver, which combines a high-gain bandwidth photo-detector and a transimpedance amplifier (preamplifier) to provide a receiver with very high dynamic range.

Agere is currently offering samples of the RA2860D, and expects to begin offering production quantities by the end of 2001.

Agere is offering two versions of the R2862 10 Gbit/s PIN receiver. The R2862D is optimised for DWDM line-side (multi-channel) applications, such as an optical core switch.

It provides a wide dynamic range with a two dBm overload. The second receiver, the R2862A, is targeted for single-channel SONET applications, such as a metro access add-drop multiplexer, and offers a sensitivity of -21 dBm.

The R2862D is a 2R receiver, integrating a limiting amplifier along with the pre-amp of a 1R receiver. A limiting amplifier is the second stage of an optical receiver, regenerating and ‘cleaning’ a signal received from the photo-detector and transimpedance amplifier.

By integrating a limiting amplifier, the receiver offers a threshold adjust feature which permits system makers to change the eye crossing point and better define the digital signal.

Like the RA2860D, samples of the R2862 receivers are available now, with production quantities expected by year’s end.

Finally, Agere’s new 12.5 Gbit/s PIN receiver, called the R2860G, has been developed to complement super FEC capability. The R2860G has a sensitivity of -18 dBm and overload of +2 dBm.

Forward-error correction uses extra bandwidth to allow receivers to detect, isolate and correct any errors created in transmission, reducing a system’s signal-to-noise ratio. Since super FEC typically uses 25 percent more bandwidth overhead, the R2860G has this added bandwidth and can maintain 10 Gbit/s transmission signals over the dynamic range.

Samples and production quantities of the R2860G are available now.

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