The SY88943V limiting post amplifier with its high gain
and wide bandwidth is ideal for use as a post amplifier in
fiber-optic receivers with data rates up to 2.5Gbps.
Signals as small as 5mVp-p can be amplified to drive
devices with PECL inputs. The SY88943V generates a
chatter-free Signal Detect (SD) open collector TTL output.
The SY88943V incorporates a programmable level detect
function to identify when the input signal has been lost.
The SD output will change from logic “HIGH” to logic “LOW”
when input signal is smaller than the swing set by SD
LVL
.
This information can be fed back to the EN input of the
device to maintain stability under loss of signal condition.
Using SD
LVL
pin, the sensitivity of the level detection can
be adjusted. The SD
LVL
voltage can be set by connecting
a resistor divider between V
CC
and V
REF
as shown in Figure
3. Figure 4, 5, 6, and 7 show the relationship between
input level sensitivity and the voltage set on SD
LVL
.
The SD output is a TTL open collector output that
requires a pull-up resistor for proper operation, Figure 1.
V
CC
SY88943V
SD
4.7kΩ to 10kΩ
Figure 1. SD Output with Desired Rise Time
BLOCK DIAGRAM
D
IN
/D
IN
Limiting
Amplifer
ECL
Buffer
D
OUT
/D
OUT
Enable
V
REF
V
CC
GND
Level
Detect
EN
SD
LVL
SD
M9999-082205
hbwhelp@micrel.com or (408) 955-1690
Rev.: C
Amendment: /0
1
Issue Date: August 2005
Micrel, Inc.
SY88943V
PACKAGE/ORDERING INFORMATION
Ordering Information
EN 1
DIN 2
/DIN 3
VREF 4
SDLVL 5
MSOP
K10-1
10 VCC
9 DOUT
8 /DOUT
7 SD
6 GND
Part Number
SY88943VKC
SY88943VKCTR
(1)
SY88943VKG
SY88943VKGTR
(1)
Note:
1.
Tape and Reel.
Package
Type
K10-1
K10-1
K10-1
K10-1
Operating
Range
Commercial
Commercial
Commercial
Commercial
Package
Marking
943V
943V
943V with
Pb-Free bar-line indicator
943V with
Pb-Free bar-line indicator
Lead
Finish
Sn-Pb
Sn-Pb
Pb-Free
NiPdAu
Pb-Free
NiPdAu
10-Pin MSOP (K10-1)
PIN NAMES
Pin
D
IN
/D
IN
SD
LVL
EN
SD
GND
/D
OUT
D
OUT
V
CC
V
REF
Type
Data Input
Data Input
Input
TTL Input
TTL Output
(Open Collector)
Ground
PECL Output
PECL Output
Power Supply
Output
Function
Data Input
Inverting Data Input
SD Level Set
Output Enable (Active High)
Signal Detect
Ground
Inverting Data Output
Data Output
Positive Power Supply
Reference Voltage Output for
SD Level Set (see Fig. 3)
GENERAL DESCRIPTION
General
The SY88943V is an integrated limiting amplifier intended
for high-frequency fiber-optic applications. The circuit
connects to typical transimpedance amplifiers found within
a fiber-optics link. The linear signal output from a
transimpedance amplifier can contain significant amounts
of noise, and may vary in amplitude over time. The
SY88943V limiting amplifier quantizes the signal and outputs
a voltage-limited waveform.
The EN pin allows the user to disable the output signal
without removing the input signal.
ABSOLUTE MAXIMUM RATINGS
(1)
Symbol
V
CC
D
IN
, /D
IN
D
OUT
, /D
OUT
EN
SD
LVL
V
REF
T
A
T
store
Rating
Power Supply Voltage
Input Voltage
Output Voltage (with 50Ω load)
Input Voltage
Input Voltage
Output Voltage
Operating Temperature Range
Storage Temperature Range
Value
0 to +7.0
0 to V
CC
V
CC
–2.5 to V
CC
+0.3
0 to V
CC
0 to V
CC
V
CC
–2.0 to V
CC
–40 to +85
–55 to +125
Unit
V
V
V
V
V
V
°C
°C
Note:
1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is not implied at
conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum ratlng conditions for extended periods
may affect device reliability.
M9999-082205
hbwhelp@micrel.com or (408) 955-1690
2
Micrel, Inc.
SY88943V
DC ELECTRICAL CHARACTERISTICS
V
CC
= +5V
±10%,
R
LOAD
= 50Ω to V
CC
–2V
T
A
= –40
°
C
Symbol
I
CC
I
IL
I
IH
V
CMR
V
offset
SD
LVL
V
OL
I
OH
V
OH
V
OL
V
REF
I
REF
V
IH
V
IL
Parameter
Power Supply
Current
(1)
5V
3.3V
Min.
—
—
–0.3
(6)
—
—
GND +2.0
—
V
REF
—
—
Max.
40
40
—
20
(4)
100
(5)
V
CC
±100
V
CC
0.5
100
T
A
= 0
°
C
Min.
—
—
–0.3
(6)
—
—
GND +2.0
—
V
REF
—
—
Max.
40
40
—
20
(4)
100
(5)
V
CC
±100
V
CC
0.5
100
Min.
—
—
–0.3
(6)
—
—
GND +2.0
—
V
REF
—
—
T
A
= +25
°
C
Typ.
33
28
—
—
—
—
±17
—
—
—
Max.
40
40
—
20
(4)
100
(5)
V
CC
±100
V
CC
0.5
100
T
A
= +85
°
C
Min.
—
—
–0.3
(6)
—
—
GND +2.0
—
V
REF
—
—
Max.
45
45
—
20
(4)
100
(5)
V
CC
±100
V
CC
0.5
100
Unit
mA
mA
µA
V
mV
V
V
µA
mV
mV
V
mA
V
V
EN Input LOW Current
EN Input HIGH Current
Common Mode Range
Differential Output Offset
SD
LVL
Level
SD Output Low Level
(2)
SD Output Leakage
(3)
D
OUT
and /D
OUT
HIGH Output
D
OUT
and /D
OUT
LOW Output
Reference Supply
V
REF
Output Current
EN Input HIGH Voltage
EN Input LOW Voltage
V
CC
-1085 V
CC
-880 V
CC
-1025 V
CC
-880 V
CC
-1025 V
CC
-955 V
CC
-880 V
CC
-1025 V
CC
-880
V
CC
-1830 V
CC
-1555 V
CC
-1810 V
CC
-1620 V
CC
-1810 V
CC
-1705 V
CC
-1620 V
CC
-1810 V
CC
- 1620
V
CC
-1.38 V
CC
-1.26 V
CC
-1.38 V
CC
-1.26 V
CC
-1.38 V
CC
-1.32 V
CC
-1.26 V
CC
-1.38 V
CC
-1.26
–0.8
2.0
—
0.5
—
0.8
–0.8
2.0
—
0.5
—
0.8
4. V
IN
= 2.7V
5. V
IN
= V
CC
6. V
IN
= 0.5V
–0.8
2.0
—
—
—
—
0.5
—
0.8
–0.8
2.0
—
0.5
—
0.8
Notes:
1. No output load
2. I
OL
= + 2mA
3. V
OH
= 5.5V
AC ELECTRICAL CHARACTERISTICS
V
CC
= +5V
±10%,
R
LOAD
= 50Ω to V
CC
–2V
T
A
= –40
°
C
Symbol
PSRR
V
ID
V
OD
t
ONL
t
ONH
t
OFFL
V
SR
HYS
t
r
, t
f
Parameter
Power Supply
(1)
Rejection Ratio
Input Voltage Range
Differential Output
Voltage Swing
(2)
SD Release Time
(3)
Minimum Input
SD Release Time
(4)
Maximum Input
SD Assert Time
(3)
SD Sensitivity Range
SD Hysteresis
Output Rise/Fall Time
Min.
—
5
—
—
—
—
—
5
2
—
—
Max.
—
1800
—
—
0.5
0.5
0.5
50
8
175
—
T
A
= 0
°
C
Min.
—
5
—
—
—
—
—
5
2
—
—
Max.
—
1800
—
—
0.5
0.5
0.5
50
8
175
—
—
5
—
—
—
—
—
5
2
—
—
T
A
= +25
°
C
Min.
Typ.
35
—
700
300
0.2
0.2
0.1
—
4.6
150
t
rin
,t
fin
Max.
—
1800
—
—
0.5
0.5
0.5
50
8
175
—
T
A
= +85
°
C
Min.
—
5
—
—
—
—
—
5
2
—
—
Max.
—
Unit
dB
Conditions
Input referred,
55MHz
1800 mV
PP
—
—
0.5
0.5
0.5
50
8
175
—
mV
mV
µs
µs
µs
mV
PP
dB
ps
2
23
-1 pattern
2
23
-1 pattern
V
ID
> 100mV
PP
V
ID
< 100mV
PP
V
ID
= 15mV
PP
V
ID
= 5mV
PP
Notes:
1. Input referred noise = RMS output noise/low frequency gain.
2. Input is a 622MHz square wave.
M9999-082205
hbwhelp@micrel.com or (408) 955-1690
3. Input is a 200MHz square wave, tr < 300ps, 8mV
PP
.
4. Input is a 200MHz square wave, tr < 300ps, 1.8V
PP
.
3
Micrel, Inc.
SY88943V
DESIGN PROCEDURE
Output Termination
The SY88943V outputs must be terminated with a 50Ω
load to V
CC
–2V (or Thevenin equivalent).
Layout and PCB Design
Since the SY88943V is a high-frequency component,
performance can be largely determined by the board layout
and design. A common problem with high-gain amplifiers is
the feedback from the large swing outputs to the input via
the power supply.
The SY88943V ground pin should be connected to the
circuit board ground. Use multiple PCB vias close to the
part to connect to ground. Avoid long, inductive runs which
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