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Original question:

1G Optical module reference schematics and layout guide

WEBENCH® Tools/ONET4291TA: Trans impedance with AGC

Shashikant Prajapati
Prodigy 110 points
Part Number: ONET4291TA
Other Parts Discussed in Thread: VCA810

Tool/software: WEBENCH® Design Tools

Hello TI Team,

We are working on project based on visible light communication, for that we have a requirement of trans-impedance amplifier which can convert current into voltage with automatic gain control circuit.

auto gain control is required if receiver circuit(photo-diode) is move within some distance, so we are decided to select IC having part number #ONET4291TA.

Our transmitter will transmit data at 10kHz frequency, hope this device support this frequency for better communication. we already read the datasheet but still have some doubt.

Question:

1) Can this IC receive data without any loss using photo-diode because transmitter which is transmitting light on the photo-diode circuit is in moving within 1 meter?

2) As mentioned in datasheet output is analog and differential, if we want only positive output can we connect negative output with ground?

3) This IC will deliver fix output voltage using internal AGC??

4) if possible share me the reference schematic for the same.

  • 0
    TI__Mastermind 22420 points

    Hello Shashikant, 

        I believe you were looking for devices for this same application in a previous thread. From my understanding, you are leaning towards choosing a ONET parts because it has an internal AGC. I would recommend not using a high bandwidth part such as the ONET4291TA  for a 10kHz input signal. There are many complexities which come with high speed parts especially with the ONET devices which have bandwidths in the GHz. Also, the ONET device is only available in die form, so you will need to be able to accommodate bonding the die onto a substrate. The output is stage consist of CML output buffer which is used to interface with on-chip transmission lines for fast data transmission in mainly fiber optic components. 

         I would recommend the VCA810 instead. Figure 36 in the VCA810 datasheet has a reference schematic for a wide-range AGC amplifier. 

    Thank you,

    Sima 

  • 0
    TI__Mastermind 22420 points

    Hello Shashikant, 

       Were you able to look into the VCA810? Do you have any concerns?

    Thank you,
    Sima

  • 0
    TI__Mastermind 22420 points

    Hello Shashikant, 

       I will be closing this thread due to inactivity. Please post a reply or start a new thread if further discussion is needed.

    Thank you,

    Sima