
DATA SHEET
ICS874001AGI-02 REVISION A AUGUST 30, 2010
1
2010 Integrated Device Technology, Inc.
PCI Express Jitter Attenuator
ICS874001I-02
General Description
The ICS874001I-02 is a high performance Jitter Attenuator designed
for use in PCI Express systems. In some PCI Express systems,
such as those found in desktop PCs, the PCI Express clocks are
generated from a low bandwidth, high phase noise PLL frequency
synthesizer. In these systems, a jitter attenuator may be required to
attenuate high frequency random and deterministic jitter
components from the PLL synthesizer and from the system board.
The ICS874001I-02 has two different PLL bandwidth modes: 2MHz
and 3MHz. The 2MHz mode will provide maximum jitter attenuation,
but with higher PLL tracking skew and spread spectrum modulation
from the motherboard synthesizer may be attenuated. The 3MHz
bandwidth provides the best tracking skew and will pass most
spread profiles, but the jitter attenuation will not be as good as the
lower bandwidth mode. The 874001I-02 can be set for different
modes using the F_SELx pins, as shown in Table 3C.
The ICS874001I-02 uses IDT’s 3RD Generation FemtoClock
PLL technology to achieve the lowest possible phase noise. The
device is packaged in a small 20-pin TSSOP package, making it
ideal for use in space constrained applications such as PCI Express
add-in cards.
Features
One differential LVDS output pair
One differential clock input
CLK, nCLK can accept the following differential input levels:
LVPECL, LVDS, LVHSTL, HCSL, SSTL
Input frequency range: 98MHz to 128MHz
Output frequency range: 98MHz to 640MHz
VCO range: 490MHz - 640MHz
Cycle-to-cycle jitter: 15ps (maximum), 3.3V
RMS period jitter: 3ps (maximum), 3.3V
Two bandwidth modes allow the system designer to make jitter
attenuation/tracking skew design trade-offs
Full 3.3V or 2.5V operating supply
-40°C to 85°C ambient operating temperature
Available in lead-free (RoHS 6) package
PLL Bandwidth Control Table
PLL_SEL Control Table
BW_SEL
0 = PLL Bandwidth: 2MHz (default)
1 = PLL Bandwidth: 3MHz
PLL_SEL
0 = Bypass
1 = VCO (default)
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
F_SEL0
VDDA
F_SEL1
BW_SEL
MR
nc
PLL_SEL
VDD
nc
VDDO
Q
nQ
nc
GND
nCLK
CLK
OE
Pin Assignment
ICS874001I-02
20-Lead TSSOP
6.5mm x 4.4mm x 0.925mm package body
G Package
Top View