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2.5Gbps HIGH-SPEED LIMITING POST AMPLIFIER
SY88923
FEATURES
s s s s s s s s Up to 2.5Gbps operation Low noise Chatter-Free LOS generation Open Collector TTL LOS output TTL /EN Input Differential PECL inputs for data Single power supply Designed for use with SY88922 and SY88904 or SY88905 s Available in a tiny 10-pin (3mm) MSOP
DESCRIPTION
The SY88923 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 SY88923 generates a chatter-free Loss of Signal (LOS) open collector TTL output. The SY88923 incorporates a programmable 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 condition. Using LOSLVL pin, the sensitivity of the level detection can be adjusted. The LOSLVL voltage can be set by connecting a resistor divider between VCC and VREF. Figure 3 and Figure 4 show 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. The LOS output is a TTL open collector output that requires a pull-up resistor for proper operation, Figure 1.
+5.0V SY88923 LOS 2k
PIN CONFIGURATION
/EN 1 DIN 2 /DIN 3 VREF 4 LOSLVL 5 MSOP K10-1 10 VCC 9 DOUT 8 /DOUT 7 LOS 6 GND
Figure 1. LOS Output with Desired Rise Time
APPLICATIONS
s s s s s 1.25Gbps Gigabit Ethernet 531Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit interface converter 2.5Gbps SDH/SONET
BLOCK DIAGRAM
DIN
Limiting Amplifer ECL Buffer
DOUT DOUT
DIN VREF
Enable
VCC GND
Level Detect
EN
LOSLVL
LOS
Rev.: C
Amendment: /1
1
Issue Date: July 2000
Micrel
SY88923
PIN NAMES
Pin DIN /DIN LOS LVL /EN LOS GND /DOUT DOUT VCC VREF 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 LOS Limit Set Output Enable (Active Low) Loss of Signal Indicator (Active High) Ground Inverting Data Output Data Output Positive Power Supply Reference Voltage Output for LOS Level Set (see Fig. 3)
GENERAL DESCRIPTION
General The SY88923 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 SY88923 limiting amplifier quantizes the signal and outputs a voltagelimited waveform. The /EN pin allows the user to disable the output signal without removing the input signal.
ABSOLUTE MAXIMUM RATINGS(1)
Symbol VCC DIN, /DIN DOUT, /DOUT TA Tstore Rating Power Supply Voltage Input Voltage Output Voltage (with 50 load) Operating Temperature Range Storage Temperature Range Value 0 to +7.0 0 to VCC VCC -2.5, VCC +0.3 -40 to +85 -55 to +125 Unit 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.
2
Micrel
SY88923
DC ELECTRICAL CHARACTERISTICS
VCC = +5V 10%, RLOAD = 50 to VCC-2V, TA = -40C to +85C
TA = -40C Symbol ICC IIL IIH VCMR Voffset LOSLVL VOL IOH VOH VOL VREF VIH VIL Parameter Power Supply Current(1) Min. -- -0.3(8) -- -- Max. 35 -- 20(5) 100(6) 100 VCC 0.5 250 TA = 0C Min. -- -0.3(8) -- -- Max. 35 -- 20(5) 100(6) 100 VCC 0.5 250 Min. -- -0.3(8) -- -- TA = +25C Typ. 21 -- -- -- -- -- -- -- -- Max. 35 -- 20(5) 100(6) 100 VCC 0.5 250 TA = +85C Min. -- -0.3(8) -- -- Max. 35 -- 20(5) 100(6) V mV V V uA mV mV V V V 100 VCC 0.5 250
VCC-880
Unit mA mA A
/EN Input LOW Current /EN Input HIGH Current Common Mode Range Differential Output Offset LOSLVL Level(2) Level(3) Leakage(4)
GND +2.0 VCC -1.0 GND +2.0 VCC -1.0 GND +2.0
VCC -1.0 GND +2.0 VCC -1.0 -- VREF -- --
-- VREF -- --
VCC-1085
-- VREF -- --
-- VREF -- --
LOS Output Low LOS Output
DOUT and /DOUT HIGH Output DOUT and /DOUT LOW Output Reference Supply(7) /EN Input HIGH Voltage /EN Input LOW Voltage
VCC-880 VCC-1025 VCC-880 VCC-1025 VCC-955 VCC-880 VCC-1025
VCC-1830 VCC-1555 VCC-1810 VCC-1620 VCC-1810 VCC-1705 VCC-1620 VCC-1810 VCC-1620 VCC-2.625 VCC-2.325 VCC-2.625 VCC-2.325 VCC-2.625 VCC-2.475 VCC-2.325 VCC-2.625 VCC-2.325
2.0 --
-- 0.8
2.0 --
5. 6. 7. 8.
-- 0.8
2.0 --
-- --
-- 0.8
2.0 --
-- 0.8
NOTES: 1. No output load. 2. 223-1 pattern. 3. IOL = + 2mA. 4. VOH = 5.5V.
VIN = 2.7. VIN =VCC. IREF must be limited within -0.8mA (source) and 0.4mA (sink). VIN = 0.5V.
AC ELECTRICAL CHARACTERISTICS
VCC = +5V 10%, RLOAD = 50 to VCC - 2V, TA = -40C to +85C
TA = -40C Symbol PSRR VID tr, tf VOD tOFFL tOFFH tONL VSR HYS Parameter Power Rejection Ratio Supply(1) Min. -- 5 -- -- -- -- -- -- -- 5 2 Max. -- 1800 175 -- -- -- 0.5 0.5 0.5 50 8 TA = 0C Min. -- 5 -- -- -- -- -- -- -- 5 2 Max. -- 1800 175 -- -- -- 0.5 0.5 0.5 50 8 -- 5 -- -- -- -- -- -- -- 5 2 TA = +25C Min. Typ. 35 -- -- trin,tfin 600 200 0.1 0.1 0.2 -- 4.6 Max. -- 1800 175 -- -- -- 0.5 0.5 0.5 50 8 TA = +85C Min. -- 5 -- -- -- -- -- -- -- 5 2 Max. -- Unit dB Conditions Input referred, 55MHz
Input Voltage Range Output Rise/Fall Time Differential Output Voltage Swing(2) LOS Release Time(3) Minimum Input LOS Release Time(4) Maximum Input LOS Assert Time(3) LOS Sensitivity Range LOS Hysteresis
1800 mVp-p 175 -- -- -- 0.5 0.5 0.5 50 8 ps mV mV s s s mVp-p dB 223-1 pattern VID > 100mVp-p VID < 100mVp-p VID = 15mVp-p VID = 5mVp-p
NOTES: 1. Input referred noise = RMS output noise/low frequency gain. 2. Input is a 622MHz square wave.
3. Input is a 200MHz square wave, tr < 300ps, 8mVp-p. 4. Input is a 200MHz square wave, tr < 300ps, 1.8Vp-p.
3
Micrel
SY88923
DESIGN PROCEDURE
Output Termination The SY88923 outputs must be terminated with a 50 load to VCC - 2V (or thevenin equivalent). Layout and PCB Design Since the SY88923 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 power supply. The SY88923 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.
PERFORMANCE CURVE
LOS Assert and Deassert Levels vs LOSLVL
100.00 90.00 80.00 70.00
Deassert
Level (mV)
60.00 50.00 40.00 30.00 20.00 10.00
Assert
4.01
4.13
4.26
4.38
4.51
4.63
4.75
4.88
0.95
2.53
2.65
2.77
2.90 3.02
3.14 3.27
LOSLVL (V)
0.1F 0.1F
DIN+ DIN- 50 VREF
Figure 4. 223-1 Pattern
50
0.1F
100.00 90.00
LOS Assert and Deassert Levels vs Resistor Divide
Figure 2. Differential Input Configuration
80.00 70.00
3.64 3.76
3.39
3.52
3.89
5.00
0.00
Deassert
Level (mV)
60.00 50.00 40.00 30.00 20.00
Assert
VCC
R1 LOSLVL R2 VREF
10.00 0.00
0.00 0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
Resistor Divider R2 / (R1 + R2)
Figure 5. 223-1 Pattern
NOTE: Resistor Divider = R2/ (R1 + R2) R1 + R2 5k Figure 3. LOSLVL Circut
4
1.00
SY88923
20k
1000pF
VCC
68 68
PRODUCT ORDERING CODE
Photodiode
Laserdiode
VCC VREF OUT DIN DIN RSET
Package Type
RSER
BLM21A102S
TX_DATA+
SY88922
EN
200
200
TX_DATA-
OUT
REXT
24
Laser Module
ENABLE/DISABLE
VCC
GND
VCC
APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION
GBIC Terminal
IBIAS
MD IBIAS SET
20k
The value of RSER depends on the Laser Diode.
SY88905
LOSOUT LOSIN
RX_LOS
IBIAS FB IPIN SET
20k
SY88923KC
Ordering Code
K10-1
Commercial
Operating Range
VCC VCC
68 68
GND
VREF VCC
82
DIN DOUT DOUT
RX_DATA+ RX_DATA-
200 200
130
LOSLVL
0.1F
VCC
0.1F
VCC
GND
VREF
Micrel
20k
130
SY88923
DIN
82
EN
LOS
5
Micrel
SY88923
10 LEAD MSOP (K10-1)
Rev. 00
6
Micrel
SY88923
7
Micrel
SY88923
MICREL-SYNERGY
TEL
3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA
+ 1 (408) 914-7878
WEB
+ 1 (408) 980-9191
FAX
http://www.synergysemi.com 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. (c) 2000 Micrel Incorporated
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