LVPECL

150

(2)

W

50

(2)

W

LVDS

LVDS

100 W

LVDS

100 W

LVCMOS

22 W

LVCMOS

CDCM9102

SCAS922

– FEBRUARY 2012

www.ti.com

Figure 16. LVPECL Output Termination (AC-Coupled)

LVDS TERMINATION

The proper LVDS termination for signal integrity over two 50-

Ω lines is 100 Ω between the outputs on the

receiver end. Either a direct-coupled (dc) termination or ac-coupled termination can be used for LVDS outputs,

as shown in Figure 17 and Figure 18. It is recommended to place all resistive components close to either the

driver end or the receiver end. If the supply voltages of the driver and receiver are different, ac coupling is

required.

Figure 17. LVDS Output Termination (DC Coupled)

Figure 18. LVDS Output Termination (AC Coupling)

LVCMOS TERMINATION

Series termination is a common method to maintain the signal integrity for LVCMOS drivers, if connected to a

receiver with a high-impedance input. For series termination, a series resistor, Rs, is placed close to the driver,

as shown in Figure 19. The sum of the driver impedance and Rs should be close to the transmission-line

impedance, which is usually 50

Ω. Because the LVCMOS driver in the CDCM9102 has an impedance of 30 Ω,

Rs is recommended to be 22

Ω to maintain proper signal integrity.

Figure 19. LVCMOS Output Termination

14

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