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Current mirror or Current source

Wang Carson
Prodigy 165 points

Hi   

I am studying on the current mirror (224 in Fig 2) described in TI's patent (patent No. US 6,925, 171B2), which appears to be a controlled current source.Oddly, though, it is a four-port network and has no common reference point for universal current mirrors.This is causing me some confusion.

Could you recommend the  suitable  Part number of TI?

Br,

Carson 

US6925171 UNIVERSAL IMPEDANCE MATCHING network for the subscriber line integrated circuits.pdf

  • 0
    TI__Mastermind 35620 points

    Hi Carson,

    It seems this is an integrated solution and there is not a TI part number for the suitable current source, if that is what you’re asking for.

    Concerning the current source itself - unless I misunderstood, the common reference point is ground – with the input side grounded directly and the output side forced by virtual ground.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 165 points

    Hi Guang，

    Thanks for response，

    If there is't uitable part, I had to build  current mirror .I don't think it's hard to build a current mirror in theory.

    However,in general , current mirror should be  a 3-PORT network  with  one input terminal connnected to the control current source AND another port tied to ground..In the output aspect, only one is used as the controlled current terminal.The other reference point is directly connected to the input reference point (ground) inside the current mirror. Do you mean that the virtual reference on the output side is provided by 1 or 2 in the picture below? The non-inverting inputs of  two Opmaps are tied to ground, so that  the inverting termianal of two Opamps   are get the same ground level ?

    Carson

  • 0 in reply to Wang Carson
    TI__Mastermind 35620 points

    Hi Carson,

    Yes that’s what I meant, based on the block diagram. I wish the document had details on implementation though.

    Regards, Guang

  • +1 in reply to Guang Zhou
    Prodigy 165 points

    Hi  Guang

    Unfortunately, the documentation does not include implementation details for this current mirror.But thank you