M02066 datasheet(11/20 Pages) MA-COM

11 / 20 page

Functional Description

02066-DSH-001-D

Mindspeed Technologies

Preliminary Information / Mindspeed Proprietary and Confidential

3.3

Modulator

The M02066 modulation output is optimized for driving a 25

Ω 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 RSHUNT = 39Ω, CSHUNT = 3.9 pF.

These values will need to be optimized for a specific laser.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. See

Figure 3-1.

The modulator output stage is designed to drive up to 85mA in either AC-coupled or DC-coupled mode. DC-

coupled performance depends on the laser used.

RMODSET determines the modulation current according to the following formula: IMOD = 350/RMODSET

Figure 3-2 shows the modulation current for a given RMODSET resistor.

Figure 3-2.

Modulation Current vs. RMODSET

Modulation C urrent in m A

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

1020

3040

Rmodse t (kohms)

M02066 Datasheet(PDF) 11 Page - M/A-COM Technology Solutions, Inc.