Electronic Design

NRZ-RZ Optical Module Doubles Distance Between Fiber Amplifiers

Compared to standard nonreturn-to-zero (NRZ), return-to-zero (RZ) line coding can double the distance a fiber-optic system transmits data between amplifiers. This extended "reach" lowers overall system cost and complexity. The problem, though, is that the design of NRZ-to-RZ converters and modulator drivers requires nitty-gritty discrete component analysis and testing.

Crafted by iTerra Communications, the iT-6130 eliminates this problem by incorporating an NRZ-to-RZ data converter plus a lithium-niobate modulator driver. It consists of a single-chip gallium-arsenide monolithic converter and a hybrid traveling-wave FET amplifier, plus ancillary components mounted on a substrate with high thermal conductivity. The device can be used at data rates up to 11.5 Gbits/s. A surface-mount two-chip solution and a module with surface-mounted assembly (SMA) connectors are available (see the figure).

The iT-6130 accepts NRZ data from 9 to 11 Gbits/s with 0 to −0.8 V dc. The clock input is ac-coupled. A 5- to 8-V dc control input provides output variation from 4 to 6.7 V p-p. The device also offers a jitter control input to adjust output duty cycle. Jitter is less than 3.5 ps p-p. The output is ac-coupled inverted RZ, where binary 0 is high and binary 1 is negative-going. Required dc power is +10 V (200 mA) and −4.5 V (550 mA).

The product and a development board for the surface-mount version are available now. Pricing is $360 in 1000-unit quantities.

iTerra Communications

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