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ADC08B3000RB, Balun for alternative

Shinichi Inoue
Guru 21721 points
Other Parts Discussed in Thread: ADC08B3000, LMH5401, LMH6555

Dear Specialists,

My customer is considering ADC08B3000.

He is designing evaluation circuit using ADC08B3000RB as a reference.

A Balun is used ADTL2-18(Mini Circuit), he wants to use JA4220-AL(Coilcraft).

Is it possible to use for alternative?

Are there tips, tricks and traps?

I think it's possible to change, because JA4220-AL operating frequency is wider than ADTL2-18, but I don't know further information.

I appreciate your great help.

Best regards,

Shinichi

ja4220.pdf

ADTL2-18.pdf

  • 0
    TI__Guru* 91947 points

    Shinichi,

    The JA4220-AL is a much smaller part. Is the customer's board already built? If so, it may not be possible to swap these out. Also this part is a 1:1 transformer and the board impedance/termination might not be correct for this part since the ADTL2-18 is a 2:1 device. If their board has not been built yet, I see no reason why they couldn't use this part if they provide the correct termination, impedance and footprint.

    Regards,

    Jim  

  • 0 in reply to jim s
    Guru 21721 points

    Dear Jim

    Thank you for your reply.

    In this case, the customer is considering new  design. 

    I think it is considerable.

    As you mentioned, each package is different, it can't be change for EVM.

    The customer is first design for PLL, it might be a big challenge.

    I appreciate your great help.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 44680 points

    Hi Shinichi

    A 1:1 balun can be used, but in that case a 100 ohm resistor should be connected between the + and - terminals of the balun differential output port.

    This resistance in parallel with the 100 ohm termination of the ADC inputs will give a total of 50 ohms at the balun outputs. Since the balun is likely being driven with a 50 ohm source this will provide the proper impedance matching at the input and output ports of the balun.

    Best regards,

    Jim B

  • 0 in reply to Jim Brinkhurst1
    Guru 21721 points

    Dear Jim

    Thank you for your reply.

    I'll send your advise to my customer.

    Also he has an additional request.

    Could you please advise?

    He wants to use a differential amplifier for single-end to differential.

    Because he is not familiar with a balun. 

    Do you have any reference circuit?

    Best regards,

    Shinichi 

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 44680 points

    Hi Shinichi

    The datasheets for the LMH5401 (best bandwidth and performance) and LMH6555 (lower bandwidth and performance) have example circuits showing those amplifiers configured to drive ADCs similar to the ADC08B3000 with single-ended to differential configurations. The ADC08B3000 datasheet itself also has some information on this topic.

    For detailed circuit information please refer to the schematics for the TSW12J54EVM and the ADC08B3000RB.

    Best regards,

    Jim B

  • 0 in reply to Jim Brinkhurst1
    Guru 21721 points

    Dear Jim

    Thank you for your reply and helpful information.

    I think LMH5401 will fit ADC08B3000 CLK.

    I'll introduce LMH5401 to the customer.

    I appreciate your great help.

    Best regards,

    Shinichi