VSC8121QI VITESSE [Vitesse Semiconductor Corporation], VSC8121QI Datasheet - Page 2

• Manufacturer Part Number: VSC8121QI
• Description: 2.488GHz SONET/SDH Clock Generator
• Manufacturer: VITESSE [Vitesse Semiconductor Corporation]

Page 2
2.488GHz SONET/SDH
Clock Generator
Applications Information
High-Speed Clock Output
typically results in less noise generation than square pulses in most customer applications. Figure 1 shows a typ-
ical, single-ended clock output waveform produced by the device.
pair designed to drive a 50
50 on-chip to prevent reflections.
tion methods that may be employed, depending on the particular application. Either DC-coupling (termination
#1 in Figure 3) or one of two AC coupling methods (terminations #2 and #3) may be used. As indicated, Vitesse
recommends termination #2 for AC-coupling.
The differential clock output waveforms produced by the VSC8121 are sinusoidal in nature, by design. This
CO and CON are high-speed CML outputs. As shown in Figure 2, the output driver consists of a differential
Careful layout of these signals is required for optimal performance. Figure 3 demonstrates various termina-
© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Figure 1: Typical Clock Output (CO) Waveform
Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]
transmission line environment. Note that the output driver is back terminated to
VITESSE
SEMICONDUCTOR CORPORATION
Internet: www.vitesse.com
100ps/div
75mV/div
VSC8121
Data Sheet
G52163-0, Rev 4.2
04/16/01