ADN2820 Question

Dear Sir/Madame

      I would like to use your TIA ADN2820 with an photo-diode. The functional block diagram proposed in Figure 1. of datasheet has the anode of photo-detector connected with input pin (IN). However, I have only access to cathode of our photo-detector and the anode is directly connected to ground. Can be this request satisfied using your TIA ADN2820, having the photo-diode correctly biased and respecting all the chip specifications? If not, may Analog propose other TIA?

Yours sincerely, Carlos Ferreira 

  • 0
    •  Analog Employees 
    on Feb 14, 2017 9:29 PM

    Dear Carlos,

    What is the max. data rate you target to support upto?

    Could you share me your selected photo-diode datasheet for a review?

    Which ROSA package you would like to bond this TIA and your photo-diode to, butterfly or TO-46, for example?

    In general, ADN2820 supports common cathode photo-diodes.

    However, the TIA IN pin voltage is clamped by an internal +0.85V. So, if this is a good reverse bias voltage

    to your photo-diode, you are welcome to try your common anode photo diode. Of course, when do this,

    you can not copy Fig. 1 circuitry directly.

    Best Regards,

    Dongfeng

  • Thank you for your fast response

    The interest bandwidth of the photo-detector signal should be between 1.4 GHz and 2.6 GHz (the data will have about 2 Gbits/s). Our photo-detector was designed using photonic integrated techniques and only has two pads: one ground and the cathode (their impedance is capacitive) . The TIA and photo-diode will be bond to "top layer" pads/tracks using one of the ROGERS substrates. We thought in connected the TIA outputs to SMA RF connectors, the grounds to PCB bottom layer using vias and the DC voltages to Right Angle SMT 2 male connectors.

    Maybe, we will need a reverse bias voltage of +2.0V. Could be a bias-T circuit a possible solution to this problem?

    Best regards,

    Carlos Ribeiro

  • Thank you for your fast response

    The interest bandwidth of the photo-detector signal should be between 1.4 GHz and 2.6 GHz (the data will have about 2 Gbits/s). Our photo-detector was designed using photonic integrated techniques and only has two pads: one ground and the cathode (their impedance is capacitive) . The TIA and photo-diode will be bond to "top layer" pads/tracks using one of the ROGERS substrates. We thought in connected the TIA outputs to SMA RF connectors, the grounds to PCB bottom layer using vias and the DC voltages to Right Angle SMT 2 male connectors.

    Maybe, we will need a reverse bias voltage of +2.0V. Could be a bias-T circuit a possible solution to this problem?

    Best regards,

    Carlos Ribeiro

  • 0
    •  Analog Employees 
    on Jun 15, 2017 5:14 PM

    Dear Caros976,

    Have you tried your photo-diode with ADN2820 yet?

    In fact, ADN2880 might be a better TIA candidate for the target application data rate range: " 1.4 GHz and 2.6 GHz (the data will have about 2 Gbits/s). "

    ADN2880 could be bonded in TO-cant, Butter-fly, and PCB without oscillation tendency, after done carefully PD to TIA bonding design.

    Best Regards,

    Dongfeng