Data Quantizer
Description
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
e e S e s a e l P
A1 DC AMP REF THRESHOLD GENERATOR
w e N r o f 4 2 6 4 L /M 2 2 6 4 L M
9 12 11 13 14
s n ig s De
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
ML4621
PIN CONFIGURATION
ML4621 24-Pin Narrow DIP (P24N)
ECL LINK MON TTL LINK MON CMP ENABLE VIN– VIN+ VDC CF2 CF1 VOUT– VOUT+ CMP+ CMP– 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 VCC INOM ISE...
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