M02067_17 Datasheet, PDF (10/20 Pages) M/A-COM Technology Solutions, Inc. – 3.3 Volt Laser Driver IC for GbE and Fibre Channel to 2.1 Gbps

M02067 -12/-13
3.3 Volt Laser Driver IC for GbE and Fibre Channel to 2.1 Gbps
Rev V4
3.2
Features
• Rise and fall times <150 ps
• DC or AC-coupled modulation drive
• Independently programmable laser bias and modulation currents
• Bias current to 100 mA and modulation current to 85 mA at V_CC = 3.3V
• Automatic laser power control, with programmable temperature compensation and ‘Slow-Start’
• Bias and modulation current monitors
• Operates with +3.3V supply
3.3
Modulator
The modulator output stage is designed to drive up to 85 mA in either AC-coupled or DC-coupled mode. DC-
coupled performance depends on the laser used.
The M02067 modulation output is optimized for driving a 25Ω load; the minimum required voltage at OUT+ and
OUT- is 0.6V. To interface with the laser diode, a matching resistor (RD) is required for impedance matching. An
RC shunt network is necessary to compensate for the laser diode parasitic inductance, thereby improving the
optical eye. Typical values are R_SHUNT = 51Ω, C_SHUNT = 3.3 pF
Any capacitive loading at the cathode of a laser diode will degrade the optical output performance. An inductor is
used to isolate the BIAS pin from the laser cathode.
Figure 3-2 shows the typical I_MOD vs R_MODSET characteristic.
Figure 3-2. Modulation Current for Given R_MODSET Resistor
120
100
80
60
40
20
0
0
4000 8000 12000 16000 20000 24000 28000 32000
RMODSET (Ω)
10
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