AND8058/D

http://onsemi.com

3

–

+

100

Ω

LVDS Signals < 250 M bits/sec

Xmitter

Receiver

A

B

Switching Between 2 LVDS Lines

1/2 NLAS4599

Figure 4. Switching Between Two LVDS Lines

Low Voltage Differential Signaling

Low Voltage Differential Signaling (LVDS) is becoming

a very popular scheme for point–to–point transfer of signals

up to 200 MHz and for distances less than 25 meters. The

LVDS signals fall under EIA–644 specifications. The LVDS

signal sits at a dc. level of about 1.25 volts and is guaranteed

to fall between 100 mV and 750 mV of differential swing.

Since the NLAS44599 provides very small insertion loss,

owing to frequency roll–off or series resistance attenuation,

it makes an ideal switch for differential pairs. The

NLAS44599 consists of two independent DPST switches;

therefore, it only takes one of this device to select between

two LVDS signals going to a single transceiver.

Figure 4 shows one–half of the

switch between two differential pairs. No biasing is required

since the LVDS specification calls for the signal to be at

roughly 1.25 V, well within the requirement of the

NLAS44599. The other half of the device may be used to

provide similar or entirely different switching functions.

Other differential signals such as Ethernet signals on a

Category 5 wire, ECL signals within the frequency range of

this device, and professional audio signals (600

Ω balanced)

may be switched in a similar manner.

Summary

On

Semiconductor

is

bringing

new,

extremely

space–efficient analog switches to the marketplace. These

devices will be used creatively by our customers to solve

difficult problems, in small spaces. Both new products, the

NLAS4599 and the NLAS44599, represent step functions in

space efficiency and functionality over existing solutions.