參數(shù)資料
型號: MAX3676
廠商: Maxim Integrated Products, Inc.
元件分類: 運動控制電子
英文描述: 622Mbps, 3.3V Clock-Recovery and Data-Retiming IC with Limiting Amplifier
中文描述: 622Mbps、3.3V時鐘恢復(fù)與數(shù)據(jù)再定時IC,帶有限幅放大器
文件頁數(shù): 12/16頁
文件大?。?/td> 181K
代理商: MAX3676
M
622Mbps, 3.3V Clock-Recovery and
Data-Retiming IC with Limiting Amplifier
12
______________________________________________________________________________________
Optical receivers, incorporating transimpedance
preamplifiers and limiting postamplifiers, can signifi-
cantly clean up the effects of dispersion and attenua-
tion. In addition, these amplifiers can provide fast
transitions with minimal aberrations to the subsequent
CDR blocks. However, these stages also add distor-
tions to the midpoint crossing, contributing to timing jit-
ter. Timing jitter is one of the most critical technical
issues to consider when developing optical receivers
and CDR circuits.
A better understanding of the different sources of jitter
helps in the design and application of optical receiver
modules and integrated CDR solutions. SDH/SONET
specifications are well defined regarding the amount of
jitter tolerance allowed at the inputs of optical receivers,
as well as jitter peaking requirements, but they do little
to define the different sources of jitter. The jitter that
must be tolerated at an optical receiver input involves
three significant sources, all of which are present in
varying degrees in typical receiver systems:
1) Random jitter (RJ)
2) Pattern-dependent jitter (PDJ)
3) Pulse-width distortion (PWD)
Random Jitter
RJ is caused by random noise present during edge
transitions (Figure 8). This random noise results in ran-
dom midpoint crossings. All electrical systems gener-
ate some random noise; however, the faster the speed
of the transitions, the lower the effect of noise on ran-
dom jitter. The following equation is a simple worst-
case estimation of random jitter:
RJ (rms) = (rms noise) / (slew rate)
Pattern-Dependent Jitter
PDJ results from wide variations in the number of con-
secutive bits contained in NRZ data streams working
against the bandwidth requirements of the receiver
(Figure 9). The location of the lower -3dB cutoff fre-
quency is important, and must be set to pass the low
frequencies associated with long consecutive bit
streams. AC-coupling is common in optical receiver
design.
When using a preamplifier with a highpass frequency
response, select the input AC-coupling capacitor, C
IN
,
to provide a low-frequency cutoff (f
C
) one decade lower
than the preamplifier low-frequency cutoff. As a result,
the PDJ is dominated by the low-frequency cutoff of
the preamplifier.
When using a preamplifier without a highpass response
with the MAX3676, the following equation provides a
good starting point for choosing C
IN
:
where t
L
= duration of the longest run of consecutive
bits of the same value (seconds); PDJ = maximum
C
-t
1.25k
(
In
)
PDJ BW
.
0 5
L
(
)
1
MIDPOINT
MIDPOINT
RANDOM
JITTER
ACTUAL
MIDPOINT
CROSSING
DESIRED
MIDPOINT
CROSSING
0–1
TRANSITION
WITH RANDOM
NOISE
TIME
A
Figure 8. Random Jitter on Edge Transition
A
TIME
MIDPOINT
LONG
CONSECUTIVE
BIT STREAM
0-1-0 BIT STREAM
LF DROOP
LF PDJ
Figure 9. Pattern-Dependent Jitter Due to Low-Frequency
Cutoff
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX3676E/D 功能描述:計時器和支持產(chǎn)品 RoHS:否 制造商:Micrel 類型:Standard 封裝 / 箱體:SOT-23 內(nèi)部定時器數(shù)量:1 電源電壓-最大:18 V 電源電壓-最小:2.7 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel
MAX3676E/D DIE 制造商:Maxim Integrated Products 功能描述:
MAX3676E/D+ 功能描述:計時器和支持產(chǎn)品 RoHS:否 制造商:Micrel 類型:Standard 封裝 / 箱體:SOT-23 內(nèi)部定時器數(shù)量:1 電源電壓-最大:18 V 電源電壓-最小:2.7 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel
MAX3676EHJ 功能描述:時鐘發(fā)生器及支持產(chǎn)品 622Mbps 3.3V Clock Recovery RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-56
MAX3676EHJ+ 功能描述:時鐘發(fā)生器及支持產(chǎn)品 622Mbps 3.3V Clock Recovery RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-56