Introduction
This document explains to use the SY88149NDL and SY88349NDL burst mode limiting amplifiers in different how
applications including 1G/10GEPON, XGPON.1, GE- -PON/GPON, Gigabit Ethernet, Fibre Channel, OC 3/12/24
SONET/SDH, and OBSAI/CPRI.
The SY88149NDL (resp. SY88349NDL) is a high sensitivity limiting post amplifier that can am- plify signals as
small as 5mVPP with data rates up to 1.25Gbps (resp. 2.5Gbps). The parts offer LOS or SD outputs depending on
the LOS/SD SEL option. The LOS/SD output can be fed back to JAM input for output stability when there is no the
data present at the input. LOS/SDLVL sets the threshold for the input signal detection.
Both amplifiers offer a fast SD assert (LOS de assert) time of 5ns and a fast SD de assert (LOS assert) time of - -
5ns if manual RESET is used or 120ns if /AUTORESET is used.
Noise Discriminator
The noise discriminator feature is intended for PON OLT applications with gain burst mode TIAs where noise -high -
can trigger a false LOS de assert or SD assert while no input data is present. The noise discriminator will filter -
input data through a series of specialized circuits that will only trigger LOS/SD on the rising edge of a valid PON
1.244Gbps noise (resp. 2.488Gbps) preamble bit stream (10101). The SY88149NDL (resp. SY88349NDL)
discriminator is designed to accept a 1.244 (resp. 2.488 preamble burst. Any Gbps 300 bps± M Gbps 300 bps)± M
other bit pattern will be rejected. If th ed at any other data rate, the noise discriminator should be is part is us
disabled.
The noise discriminator, implemented in the edge detector circuit, can be selected or bypassed by selecting the
proper resistor value using the settings at as shown in the LOS/SDSEL pin, Table 1.
Table 1. Truth Table for SD/LOS Select and Noise Discriminator function
LOS/SDSEL P LOS/SD Sin election N Doise iscriminator I To O nput JAM utputs
0 SD Ωto VCC Enabled HIGH Enabled
0 SD Ωto VCC Enabled LOW Disabled
16k DisabledΩ SD to VCC HIGH Enabled
16k DisabledΩ SD to VCC LOW Disabled
16k DisabledΩ to GND LOS HIGH Disabled
16k DisabledΩ to GND LOS LOW Enabled
0 Ωto GND LOS Enabled HIGH Disabled
0 Ωto GND LOS Enabled LOW Enabled
Micrel Inc. • 2180 Fortune Drive • Jose, CA 95131 • USA • tel +1 (408) 944 0800 • fax + 1 (408) 474 1000 • San - - http://www.micrel.com
April 23, 2014 Revision 1.1
