Inphi launches 25-Gbps differential Mach-Zehnder driver

-- Test & Measurement World, 2/4/2008 1:24:00 PM

Joining Inphi’s portfolio of optical components is the 2514DZ, a 25-Gbps differential Mach-Zehnder modulator driver. This device delivers the differential output voltage and high data rates required for next-generation 40G differential quadrature phase shift keying (DQPSK) and 100G optical communications applications.
 
The 2514DZ driver—with a differential output modulation range of 4.0 V to 8.0 V pk-pk and data rates of greater than 25 Gbps—works seamlessly with differential Mach-Zehnder modulators from Fujitsu and Sumitomo Osaka Cement Company (SOCC). The input is single-ended, and both input and outputs are internally AC coupled (DC blocked). In addition, the device supports clock frequencies of up to 25 GHz and offers output amplitude control and adjustable eye crossing.

As the transmission line rate increases from 10 Gbps to 40 Gbps, significant fiber impairments limit how far the signal can be transmitted before regeneration. For the standard Non-Return-to-Zero (NRZ) transmission method, these impairments limit the transmission distance to a few kilometers.

Unlike the NRZ transmission method, which transmits one bit of data per symbol, DQPSK encodes two bits of data per symbol, effectively cutting the transmission line rate in half. Thus, 40G DQPSK systems are less sensitive to fiber impairments than other transmission methods at the native 40-Gbps line rate and can transmit 40-Gbps data well over 1000 kilometers.

Future 100-Gbps systems may rely on even more sophisticated coding schemes to encode 4 bits of data per symbol so that 100-Gbps data can be transmitted at a line rate of approximately 25 Gbps. Inphi’s 2514DZ has been demonstrated to work beyond the minimum specification of 25 Gbps and is now being used by leading module and OEM customers worldwide in the development of such a system.

Inphi, www.inphi-corp.com.