Passive equalisers extend serial data reach on FR-4

EDN Europe, 02 Aug 2007

1st August, 2007 – Two power-saver equalisers from National Semiconductor, can effectively increase the range of high-speed serial data transmission across standard printed circuit board material. The DS38EP100 can equalise 40 in. (100 cm) of FR-4 printed circuit board (PCB) at a data transmission rate of 3.125 Gbps, a figure that National says is twice the reach of other passive equalisers. This device and its companion DS80EP100 require no power or ground routing and accept any high-speed differential signal technology, including current-mode logic (CML), low-voltage differential signalling (LVDS) and low-voltage positive emitter coupled logic (LVPECL). Bi-directional in operation, they offer the same equalisation gain in either direction. The devices come in 6-pin LLP packages for use in space- and layout-constrained systems, such as cables or connectors in medical, security and industrial imaging systems. DS38EP100 operates from 1 Gbps to 5 Gbps, while the DS80EP100 operates from 5 Gbps to 10 Gbps. They address a variety of systems using high-definition multimedia interface (HDMI) or digital visual interface (DVI) interface standards, as well as systems using a PCI Express or XAUI interface. You can cascade the devices with an active equaliser or limiting amplifier to further extend FR-4 and cable transmission links.
DS38EP100 can also equalise up to 5m of 28-AWG HDMI cable at a data rate of 3.4 Gbps. It features 7 dB of maximum boost and its input and output impedance is 100 Ohms. It supports all data coding techniques such as 8b/10b and scrambled signals. The DS80EP100 offers similar technical features and at 10 Gbps can equalise 20 in. (50 cm) inches of FR-4 and 5m of 26 AWG cable. They cost $1.30 or $1.65 (1000) each.