SY88903 [MICREL]
1.25Gbps HIGH-SPEED LIMITING POST AMPLIFIER; 1.25Gbps的高速限幅后置放大器
| 型号： | SY88903 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 1.25Gbps HIGH-SPEED LIMITING POST AMPLIFIER |
| 文件： | 总8页 (文件大小：105K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
1.25Gbps HIGH-SPEED
LIMITING POST AMPLIFIER
SY88903
FEATURES
DESCRIPTION
■ Up to 1.25Gbps operation
■ Low noise
The SY88903 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 1.25Gbps.
Signals as small as 5mVp-p can be amplified to drive
devices with PECL inputs. The SY88903 generates a
chatter-free Loss of Signal (LOS) open collector TTL
output.
The SY88903 incorporates a programmble level detect
function to identify when the input signal has been lost.
This information can be fed back to the /EN input of the
device to maintain stability under loss of signal conditions.
Using LOSLVL pin the sensitivity of the level detect can
be adjusted. The LOSLVL voltage can be set by
connecting a resistor divider between VCC and VREF,
Figure 3. Figure 4 shows the relationship between input
level sensitivity and the voltage set on LOSLVL. Figure 5
shows the relationship between input level sensitivity and
resistor divider ratio.
■ Chatter-Free LOS Generation
■ Open Collector TTL LOS Output
■ TTL /EN Input
■ Differential PECL inputs for data
■ Single power supply
■ Designed for use with SY88902 and SY88904
■ Available in a tiny 10-pin (3mm) MSOP
PIN CONFIGURATION
/EN
1
2
3
4
5
10 VCC
DIN
9
8
7
6
DOUT
The LOS output is a TTL open collector output that
requires pull-up resistor for proper operation, Figure 1.
MSOP
K10-1
/DIN
/DOUT
LOS
VREF
+5V
LOSLVL
GND
2k
SY88903
LOS
APPLICATIONS
■ 1.25Gbps Gigabit Ethernet
■ 531Mbps and 1062Mbps Fibre Channel
■ 622Mbps SONET
Figure 1. LOS Output with Desired Rise Time
■ Gigabit Interface Converter
BLOCK DIAGRAM
D
IN
D
OUT
OUT
Limiting
Amplifier
ECL
Buffer
D
D
IN
REF
CC
V
Enable
EN
V
Level
Detect
GND
LOS
LOSLVL
Rev.: G
Amendment:/1
1
Issue Date: July 2000
Micrel
SY88903
PIN NAMES
GENERAL DESCRIPTION
General
Pin
Type
Data Input
Data Input
Input
Function
Data Input
The SY88903 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 SY88903
limiting amplifier quantizes the signal and outputs a voltage-
limited waveform.
DIN
/DIN
Inverting Data Input
LOS LVL
/EN
Loss of Signal Level Set
Output Enable (active Low)
TTL Input
LOS
TTL Output
(Open Collector)
Loss of Signal Indicator
(active High)
GND
DOUT
/DOUT
VCC
Ground
Ground
The TTL /EN pin allows the user to disable the output
signal without removing the input signal.
PECL Output
PECL Output
Power Supply
Output
Data Output
Inverting Data Output
Positive Power Supply
VREF
Reference Voltage Output
for LOS Level Set (see Fig. 3)
(1)
ABSOLUTE MAXIMUM RATINGS
Symbol
Rating
Value
0 to +7.0
Unit
V
VCC
Power Supply Voltage
Input Voltage
DIN, /DIN
DOUT, /DOUT
TA
0 to VCC
V
Output Voltage (with 50Ω load)
Operating Temperature Range
Storage Temperature Range
VCC –2.5, VCC +0.3
–40 to +85
V
°C
°C
Tstore
–55 to +125
NOTE:
1. PermanentdevicedamagemayoccurifABSOLUTEMAXIMUMRATINGSareexceeded. Thisisastressratingonlyandfunctionaloperationisnotimplied
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.
2
Micrel
SY88903
DC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%, RLOAD = 50Ω to VCC-2V, TA = –40°C to +85°C
TA = –40°C TA = 0°C
Min. Max.
TA = +25°C
TA = +85°C
Min. Max.
Symbol
ICC
Parameter
Min.
Max.
35
Min.
—
Typ.
Max.
35
Unit
mA
mA
µA
Power Supply Current(1)
/EN Input LOW Current
/EN Input HIGH Current
—
35
—
—
21
—
—
35
—
IIL
–0.3
–0.3
—
–0.3
—
–0.3
IIH
—
—
20(5)
100(6)
—
—
20(5)
100(6)
—
—
—
—
20(5)
100(6)
—
—
20(5)
100(6)
VCMR
Voffset
LOSLVL
VOL
Common Mode Range
Differential Output Offset
LOSLVL Level
GND +2.0 VCC -1.0 GND +2.0 VCC -1.0 GND +2.0
—
—
—
—
VCC -1.0 GND +2.0 VCC -1.0
V
mV
V
—
VREF
—
±100
VCC
0.5
—
VREF
—
±100
VCC
0.5
—
VREF
—
±100
VCC
0.5
—
VREF
—
±100
VCC
0.5
LOS Output Low
Level(2)
V
IOH
LOS Output Leakage(3)
—
250
—
250
—
—
250
—
250
uA
VOH
DOUT and /DOUT
HIGH Output
V
CC-1085
V
CC-880
V
V
CC-1025
V
CC-880
V
V
CC-1025
V
CC-955
V
CC-880
V
CC-1025
V
CC-880
mV
VOL
DOUT and /DOUT
LOW Output
VCC-1830
VCC–1555
CC-1810
VCC–1620
CC-1810
VCC–1705 VCC–1620
VCC-1810
V
CC–1620
mV
VREF
VIH
Reference Supply(4)
V
CC-2.625
V
CC–2.325
—
V
CC-2.625 VCC–2.325
V
CC-2.625
V
CC–2.475 VCC–2.325
V
CC-2.625
V
CC–2.325
—
V
V
V
/EN Input HIGH Voltage
/EN Input LOW Voltage
2.0
2.0
—
—
2.0
—
—
—
2.0
VIL
—
0.8
0.8
—
0.8
—
0.8
NOTES:
4. IREF must be limited to be within -0.8mA (source) and 0.5mA (sink).
1. No output load
2. IOL = + 2mA
3. VOH = 5.5V
5. VIN = 2.7V
6. VIN = VCC
AC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%, RLOAD = 50Ω to VCC - 2V, TA = –40°C to +85°C
TA = –40°C TA = 0°C
Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit
TA = +25°C
TA = +85°C
Symbol
Parameter
Conditions
PSRR
Power Supply(1)
Rejection Ratio
—
—
—
—
—
35
—
—
—
dB
Input referred,
55MHz
VID
tr, tf
Input Voltage Range
Output Rise/Fall Time
5
1800
5
1800
5
—
1800
5
1800 mVp-p
—
—
350
—
—
—
350
—
—
—
200
trin,tfin
350
—
—
—
350
—
ps
VID > 100mVp-p
VID < 100mVp-p
VOD
Differential Output
Voltage Swing(2)
—
—
—
—
—
—
—
—
—
—
600
200
—
—
—
—
—
—
mV
mV
VID = 15mVp-p
VID = 5mVp-p
tOFFL
tOFFH
LOS Release Time(3)
Minimum Input
—
0.5
—
0.5
—
0.1
0.5
—
0.5
0.5
0.5
µs
µs
µs
LOS Release Time(4)
Maximum Input
—
0.5
—
0.5
—
0.1
0.5
—
tONL
VSR
LOS Assert Time(3)
LOS Sensitivity Range
LOS Hysteresis
—
5
0.5
50
8
—
5
0.5
50
8
—
5
0.2
—
0.5
50
8
—
5
50 mVp-p
dB
HYS
2
2
2
4.6
2
8
NOTES:
3. Input is a 200MHz square wave, tr < 300ps, 8mVp-p.
4. Input is a 200MHz square wave, tr < 300ps, 1.8Vp-p.
1. Input referred noise = RMS output noise/low frequency gain.
2. Input is 622MHz square wave.
3
Micrel
SY88903
APPLICATION INFORMATION
Output Termination
The SY88903 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
can degrade performance.
The SY88903 outputs must be terminated with a 50Ω
load to VCC – 2V (or Thevenin equivalent).
Layout and PCB Design
NOTES:
Resistor Divider = R2/ (R1 + R2)
R1 + R2 ≥ 5kΩ
Since the SY88903 is a high-frequency component,
performance can largely be determined by board layout
and design. A common problem with high-gain amplifiers is
feedback from the large swing outputs to the input via the
power supply.
VCC
R1
R2
D
IN
+
0.1µF
0.1µF
LOSLVL
DIN
–
V
REF
VREF
0.1µF
Figure 3. LOSLVL Circut
Figure 2. Differential Input Configuration
PRODUCT ORDERING CODE
Ordering
Code
Package
Type
Operating
Range
SY88903KC
K16-1
Commercial
4
Micrel
SY88903
PERFORMANCE CURVE
100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
Deassert
Assert
LOSlvl (V)
Figure 4. LOS Assert and Deassert Levels vs LOSLVL
100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
Deassert
Assert
Resistor Divider R2 / (R1 + R2)
Figure 5. LOS Assert and Deassert Levels vs Resistor Divider
5
Micrel
SY88903
APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION
GBIC Terminal
130Ω
130Ω
82Ω
82Ω
130Ω
130Ω
82Ω
82Ω
REXT
24Ω
Laserdiode
20kΩ
BLM21A102S
0.1µF
130Ω
82Ω
Photodiode
1000pF
130Ω
82Ω
6
Micrel
SY88903
10 LEAD MSOP (K10-1)
Rev. 00
7
Micrel
SY88903
MICREL-SYNERGY 3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA
TEL + 1 (408) 980-9191 FAX + 1 (408) 914-7878 WEB http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
© 2000 Micrel Incorporated
8
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