M908-01 Datasheet Rev 2.1
Revised 30Jul2004
M908-01
VCSO BASED GBE CLOCK GENERATOR
Product Data Sheet
GENERAL DESCRIPTION
The M908-01 is a PLL (Phase Locked Loop) based
clock generator that uses an
internal VCSO (Voltage Controlled
SAW Oscillator) to produce a very
low jitter output clock. It is ideal for
Gigabit Ethernet. The output clock
(frequency of 156.25 or 187.50MHz
for example) is provided from eight
LVPECL clock output pairs. (Specify frequency at time
of order.) The accuracy of the output frequency is
assured by the internal PLL, which phase-locks the
internal VCSO to the reference input frequency (25 or
30
MHz for example). The input reference can either
be an external crystal, utilizing the internal crystal
oscillator, or a stable external clock source such as
a packaged crystal oscillator.
FEATURES
◆ Output clock frequency from 125MHz to 190MHz
(Consult factory for frequency availability)
◆ Eight identical LVPECL output pairs
◆ Integrated SAW (surface acoustic wave) delay line
◆ Low jitter 0.7ps RMS (over 12kHz-20MHz)
◆ Ideal for Gigabit Ethernet clock reference
◆ Output-to-output skew < 100ps
◆ External XTAL or LVCMOS reference input
◆ Industrial temperature grade available
◆ Single 3.3V power supply
◆ Small 9 x 9 mm SMT (surface mount) package
PIN ASSIGNMENT (9 x 9 mm SMT)
Figure 1: Pin Assignment
SIMPLIFIED BLOCK DIAGRAM
Example Output Frequency Configurations
Ref Clock
Frequency
(MHz)
PLL
Ratio
Output
Frequency 1
(MHz)
Note 1:Specify output clock frequency at time of order
Application
20
25/4
125.00
GbE
25
156.25
10GbE
30
187.50
12GbE
N
OP
nO
External Loop Filter
M908-01
FOUT0
nFOUT0
nFOUT1
M908-01 VCSO Based GbE Clock Generator