February 1998
ML4621
Data Quantizer
GENERAL DESCRIPTION
The ML4621 data quantizer is a low noise, wideband
monolithic IC designed specifically for signal recovery
applications in fiber-optic receiver systems. It contains a
two stage wideband limiting amplifier which is capable
of accepting an input signal as low as 2mV with a 55dB
dynamic range. This high level of sensitivity is achieved
by using a DC restoration feedback loop which nulls any
offset voltage produced in the limiting amplifier.
The output stage is a high speed comparator circuit with
both TTL and ECL outputs. An enable pin is included for
added control.
The minimum signal discriminator circuit provides a link
monitor function with a user selectable reference voltage.
This circuit monitors the peaks of the input signal and
provides a logic level output indicating when the input
falls below an acceptable level. This output can be used
to disable the quantizer and/or drive an LED, providing a
visible link status.
FEATURES
s
50MHz minimum bandwidth for data rates of up to
100MBd
Can be powered by either 5V providing TTL level
outputs, or -5.2V providing ECL level outputs
Low noise design: 25µV RMS over 50MHz noise
bandwidth
Adjustable link monitor function
s
s
s
s
s
Wide 55dB input dynamic range
10ns minimum input pulse
BLOCK DIAGRAM
(Pin Configuration Shown is for PLCC Version)
10
CF1
6
5
VIN+
VIN–
VDC
8
ee
S
se
ea
l
P
A1
DC
AMP
REF
THRESHOLD
GENERATOR
ew
N
or
f
24
46
L
/M
2
62
4
L
M
9
12
11
13
14
s
gn
si
e
D
17
16
CF2
VOUT+
VOUT–
CMP+
CMP–
ECL+
ECL–
VCC
VCC TTL
28
19
A2
ECL
CMP
TTL
CMP
TTL OUT
20
CMP ENABLE
3
FILTER
23
VREF
22
VTHADJ
MINIMUM
SIGNAL
DISCRIMINATOR
ECL LINK MON
1
TTL LINK MON
2
27
INOM
26
ISET
24
CPEAK
GND TTL
18
21
GND
1
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
