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ADN2845
Datasheet (Analog Devices)
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Datasheet ADN2845 Datasheet (Analog Devices)

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10.709 Gbps High Speed Data Switch ADN2845
FEATURES Data Rates from 9.952 Gbps to 10.709 Gbps Typical Rise/Fall Time 25 ps/23 ps Bias Current Range 3 mA to 80 mA Modulation Current Range 5 mA to 80 mA Automatic Laser Shutdown, ALS CML Data Inputs 50 Internal Data Terminations
3.3 V Single-Supply Operation Driver Supplied in Die Format Only
APPLICATIONS SONET OC-192, SDH STM-64 Supports 10.667 Gbps and 10.709 Gbps FEC Rates 10 Gb Ethernet IEEE802.3ae

FUNCTIONAL BLOCK DIAGRAM

ADN2845
DATAP
50
DATAN
50

GENERAL DESCRIPTION

The ADN2845 is a 10.709 Gbps laser diode driver. The ADN2845 eliminates the need to ac-couple since it can deliver 80 mA of modulation while dc-coupled to the laser diode. It is intended to be copackaged with the laser to minimize bond lengths, which improves performance of the optical transmitter.
The ADN2845 may be used in conjunction with the ADN2844 control chip. This chipset (ADN2843) offers a unique control algorithm to control both average power and extinction ratio of the laser diode.
For transmission line applications, contact the HSN Applications Group at fiberoptic.ic@analog.com
V
CC
LD
IMODP
IBIAS
ALS
IMOD_CTRL
IBIAS_CTRL
REV. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective companies.
ADN2845-SPECIFICATIONS
(V
= 3.0 V to 3.6 V. All specifications T
ELECTRICAL CHARACTERISTICS
CC
as specified at 25ⴗC.)
Parameter Min Typ Max Unit Conditions
LASER BIAS (BIAS)
Output Current I
BIAS
380mA
Compliance Voltage 1.2 V
during ALS 10 ASee Note 1
I
BIAS
ALS Shutdown Response Time 10 s
MODULATION CURRENT (LMODP, IMODN) See Note 2
Output Current I
MOD
580mA
Compliance Voltage 1.2 V
during ALS 10 A
I
MOD
Rise Time 25 ps Fall Time 23 ps Random Jitter 170 fs rms See Note 3 Total Jitter 7.41 ps p-p See Note 4
DATA INPUTS (DATAP, DATAN)
V p-p(Single-Ended Peak-to-Peak) 300 800 mV Input Impedance 50
LOGIC INPUTS (ALS)
V
IH
V
IL
2.4 V
0.8 V
IMOD_CTRL Input See Note 5
Gain (IMOD_CTRL to I
)1015.5 A/A
MOD
Input Voltage 1.5 V
IBIAS_CTRL Input See Note 5
Gain (IBIAS_CTRL to I
)912A/A
BIAS
Input Voltage 1.5 V
SUPPLY
V
CC
I
CC
NOTES
1
In ALS mode, approximately 15 mA is sourced to the laser from the IBIAS pin, which reverse biases the laser.
2
The ADN2845 high speed specifications are measured into a 5  load.
3
RMS jitter measured with a 0000 0000 1111 1111 repeating pattern at 10.7 Gbps rate.
4
Peak-to-peak total jitter measured with a 2
5
It is recommended to decouple these pins to VCC rather than GND.
6
IBIAS = 0, IMOD = 0 (when ALS is asserted). See Power Dissipation section on page 4 for calculation of complete power dissipation.
Specifications subject to change without notice.
13
– 1 PRBS pattern with 80 CIDs input pattern at 10.7 Gbps rate.
3.0 3.3 3.6 V 75 mA See Note 6
to T
MIN
–1.0 V
CC
CC
, unless otherwise noted. Typical values
MAX
V

ABSOLUTE MAXIMUM RATINGS*

(TA = 25°C, unless otherwise noted.)
VCC to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 V
DATAP to GND . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 4.2 V
DATAN to GND . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 4.2 V
ALS to GND . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 4.2 V
IMOD_CONTROL to GND . . . . . . . . . . . . . –0.5 V to 4.2 V
IBIAS_CONTROL to GND . . . . . . . . . . . . . . –0.5 V to 4.2 V
IMODN, IMODP . . . . . . . . . . . . . . . . . . . . . . . . . V
+1.2 V
CC
Operating Temperature Range
Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature (T
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
max) . . . . . . . . . . . . . . . . . . . 150°C
J

ORDERING GUIDE

Temperature Package Qty.
Model Range Description Min.
ADN2845ACHIPS –40ºC to +85ºC Die Form 100
REV. 0–2–
ADN2845

PIN CONFIGURATION

DATAN
GND
GND
DATAP
CC
V
1
PAD PITCH: 200␮m
NC
DIE SIZE: 1140␮m ( 20␮m) ⴛ 1340␮m ( DIE THICKNESS: 0.25mm SINGLE PAD SIZE: 92␮m ⴛ 92␮m DOUBLE PAD SIZE: 151␮m ⴛ 92␮m
ALS
VCCV
ADN2845
20␮m)
IMOD_CTRL
CC
GND
GND
IBIAS_CTRL
V
CC
(IMODN TERM)
NC
IMODP
IBIAS
NC

PIN FUNCTION DESCRIPTIONS

Pin No. Mnemonic Function
1 DATAN AC-Coupled CML Data, Negative
Differential Terminal
2GND Negative Supply
3NCNo Connect. Leave floating.
4GND Negative Supply
5 DATAP AC-Coupled CML Data, Positive
Differential Terminal
6 ALS Automatic Laser Shutdown Logic Input
7IMOD_CTRL Modulation Current Control Input
(Control circuit sinks IMOD/10 from pin to GND.)
8IBIAS_CTRL BIAS Current Control Input (Control
circuit sinks IBIAS/10 from pin to GND.)
9GND Negative Supply
10 NC No Connect. Leave floating.
11 IBIAS BIAS Current
12 IMODP Modulation Current
13 NC No Connect. Leave floating.
14 V
CC
VCC Connection for IMODN Termination Resistor
15 GND Negative Supply
16 V
17 V
18 V
CC
CC
CC
Positive Supply
Positive Supply
Positive Supply

METALLIZATION PHOTOGRAPH

GNDV
V
CC
V
CC
(IMODN TERM)
NC
IMODP
IBIAS
NC
GNDIBIAS_CTRLALS IMOD_CTRL
1
DATAN
1340␮m
(ⴞ20␮m)
DATAP
GND
NC
GND
V
CC
CC
1140␮m
(ⴞ20␮m)
DIE PAD COORDINATES
Pad No. Pad Name X (␮m) Y (␮m)
1 DATAN –500.00 400.00 2 GND 3NC –500.00 0.00 4 GND
2
2
–500.00 222.00
–500.00 –222.00 5 DATAP –500.00 –400.00 6 ALS –300.00 –600.00 7IMOD_CTRL –100.00 –600.00 8IBIAS_CTRL 100.00 –600.00 9 GND 10 NC 11 IBIAS 500.00 –200.00 12 IMODP 13 NC 14 V 15 GND 16 V 17 V 18 V
NOTES
1
The reference point with x = 0, y = 0 is the center of the die.
2
Denotes double bond pad.
2
2
2
2
(IMODN TERM)2500.00 378.00
CC
2
2
CC
2
CC
2
CC
300.00 –600.00
500.00 –400.00
500.00 –30.00
500.00 178.00
300.00 600.00
100.00 600.00
–100.00 600.00
–300.00 600.00
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADN2845 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
REV. 0
–3–
ADN2845

GENERAL

The ADN2845 is a 3.3 V high speed data switch that is intended to be dc-coupled with a copackaged laser diode. Achieving best performance requires using low inductance ribbon connections between the ADN2845 and the laser.

IMOD__CRTL, IBIAS_CTRL

The operation of the ADN2845 is controlled by the two input pins called IBIAS_CTRL and IMOD_CTRL. The user should connect current sinks from each of these pins to GND.
These currents are internally mirrored and used to control the actual values for the bias and modulation currents used to drive the laser diode. It is recommended to decouple these pins to VCC instead of GND.

DATA INPUTS

Figure 1 shows a simplified schematic of the ADN2845 data inputs. The data inputs are terminated via the equivalent of a 100 internal resistor between DATAN and DATAP. This provides 50 termination for single-ended signals. The actual signal on the switching devices is attenuated by a factor of 2
internally. There is a high impedance circuit to set the common­mode voltage, which is designed to change over temperature. It is recommended that ac coupling be used to eliminate the need for matching between the common-mode voltages.

LASER SHUTDOWN

The ADN2845 ALS allows compliance to ITU-T-G958 (11/94), section 9.7. When ALS is asserted, both bias and modulation currents are turned off. In ASL mode, approximately 15 mA is sourced to the laser from the IBIAS pin, which reverse biases the laser and ensures that it is turned off. ALS should have a 10 kW pull-down resistor connected and should be driven with correct logic levels (see Specifications section). The ALS pin should never be left floating.

POWER DISSIPATION

The power dissipation of the ADN2845 can be calculated using the following expressions:
ImAImAImA
=+¥ +¥75 1 75 0 3.().()
CC MOD BIAS
IA
()
PV I A V
=¥ + ¥ + ¥()
CC CC IMOD
where V V
IBIAS
is the average voltage on the IMOD pin, and
IMOD
is the average voltage on the IBIAS pin.
MOD
VIA
2
IBIAS BIAS
()
DATAN
DATAP
25
25
25
25
2k
ADN2845
INTERNAL REFERENCE
Figure 1. Simplified Schematic of the Data Inputs
V
V
CC
CC
VCCV
10nF
CC
GND
1518
IMODNTERM
14
10nF
DATAN
GND
10nF
CC
V
1
ADN2845
GND
10nF
DATAP
5
10k
6
ALS
V
IMOD_CTRL
CC
IBIAS_CTRL
10nF10nF
V
10
9
GND
CC
Figure 2. ADN2845 Application Circuit
V
CC
10F TANTALUM
V
CC
10nF
IMODP
IBIAS
V
CC
LD
REV. 0–4–
ADN2845
PARALLEL PLATE DECOUPLING CAPACITOR
GROUND PLANE
MPD
50  TRANSMISSION LINE
GROUND PLANE
18 15
V
V
CC
CC
DATAN
1
AGND
ADN2845
AGND
DATAP
5
AGNDV
CC
IMODNTERM
BACK FACET LIGHT
14
V
CC
IMODP
IBIAS
10
AGNDALS IMOD_CTRL IBIAS_CTRL
96
IBIAS OUTPUT INDUCTOR
PARALLEL PLATE DECOUPLING CAPACITORS
CERAMIC WITH GOLD SURFACE THAT CONTACTS THE LASER’S ANODE
LASER LIGHT
LASER
NOTES
• FOR OPTIMUM PERFORMANCE, RIBBON BONDS ARE RECOMMENDED ON PADS 1, 5, 1 2, AND 14 . WIRES ARE 3 MIL OR 5 MIL RIBBONS <400m
• LONG. ALL OTHER PINS CAN BE ROUND WIRE <1mm.
• LASER’S ANODE IS CONNECTED TO V
• 12 AND PAD 14 RIBBONS.
• PARALLEL PLATE DECOUPLING CAPACITORS SHOULD BE >100pF AND BE OF MICROWAVE AVX TYPE, PART NO. GB0159391KA6N (390pF).
• THE RECOMMENDED SUBSTRATE CONNECTION IS TO GND. HOWEVER, PERFORMANCE IS NOT AFFECTED BY CONNECTING THE
• SUBSTRATE TO VCC.
• AN INDUCTOR SHOULD BE USED IN THE BIAS CURRENT PATH. A MICROWAVE COMPONENTS COIL 30-1847-GCCAS-01 (48 MIL 24 MIL) SHOULD BE USED.
• THE EXTERNAL POWER SUPPLY IS CONNECTED AT THE PARALLEL PLATE DECOUPLING CAPACITOR.
THROUGH GOLD LAYER ON TOP OF CERAMIC STANDOFF. STANDOFF MINIMIZES LENGTH OF PAD
CC
Figure 3. Recommended Layout
REV. 0
Figure 4. 10 Gbps Optical Diagram Provided Courtesy of NEL. P
= 0 dBm, ER = 5 dB, PRBS 31 Pattern.
AV
–5–
ADN2845

OUTLINE DIMENSIONS

18-Pad Bare Die
Dimensions shown in micrometers and millimeters
1
ADN2845
PAD PITCH: 200m DIE SIZE: 1140m (20m) 1340m (20m) DIE THICKNESS: 0.25mm SINGLE PAD SIZE: 92m  92m DOUBLE PAD SIZE: 151m  92m
1140m (20m)
0.25 mm
1340m (20m)
REV. 0–6–
–7–
C03082–0–4/03(0)
–8–
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