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Laser diode driving

JC Jung
Prodigy 220 points

Other Parts Discussed in Thread: OPA861, OPA615, OPA2673

Hi.

I would like to make a laser diode driving circuit for M5-905-0100.

I want drive the laser diode with current varying from 20 to 200mA.

Applied signal is 225MHz PAM.

Can I use OPA861 and high speed transistor for driving above laser diode?

  • 0
    TI__Genius 13335 points

    Hello JC,

    A similar question has been addressed before here: http://e2e.ti.com/support/amplifiers/high_speed_amplifiers/f/10/t/100353.aspx#354423

    The OPA861 wouldn't have the output capability to source/sink +/-15mA on a 10V supply. You would need at least 14 of these in parallel to achieve 200mA of output drive. Also, it looks like the OPA861 was compensated for a gain of +5 to give a bandwidth of 80MHz, so your circuit might show some signs of instability if you try to lower the gain.

    If you are ok with using multiple in parallel, a better option might be the OPA615 which has been compensated to be unity gain stable @ 230Mz Large-Signal Bandwidth (B to C). The output drive capability is +/-20mA, so you would still need 10x in parallel. The OPA615 also has some extra biasing circuitry which allows you to control the operating current of the OTA as well as the BW and AC behavior to help tune the circuit performance.

    Another option would be to use the OPA2673 as suggested in the referenced post, which has a 1A output drive capability and is unity gain stable @ 600MHz.

    Please let me know if this has answered your question.

    Regards,
    Luke Lapointe
    High Speed Amplifiers

  • 0 in reply to Luke LaPointe
    Prodigy 220 points

     

     Hello Luke,

     Thanks for your reply on my question.

     I had reviewed your suggestions about OP AMPs and I think OPA2673 may worth try to my design further.

     Please can you help me to receive evaluation board mentioned on the data sheet of OPA2673?

    Thanks for your recommendations.

     JC Jung