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TDC1000-TDC7200EVM: Doubt with impedance matching circuit

Prudhvi Sagar
Genius 3785 points
Part Number: TDC1000-TDC7200EVM


Hello,

I am unable to understand the working of the impedance matching circuit which uses switch as TS3A44159, can you please explain the basic working. Can the board be re-designed using through-hole components aswell?

Regards,

Prudhvi Sagar

  • 0
    TI__Mastermind 31655 points

    Hi Prudhvi,

    I explain the function of the individual components in this thread:

    The switching is described in the application note, and clearly presented in this diagram:

  • 0 in reply to Scott Cummins
    Genius 3785 points

    Hello sir,

    I have understood the working of impedance matching circuit. Is the main role of the interface is to add these extra components or is it meant for a bigger purpose (with the whole switching mechanism)? EVM already has the components 300pf and 200 ohms, so having them again in the interfacing board would cause any issue?

    Regards.

    Prudhvi Sagar

  • 0 in reply to Prudhvi Sagar
    TI__Mastermind 31655 points
    Hi Prudhvi,

    The switching and the passive components are both important parts of the impedance matching circuit. As shown in the diagram, the switching ensures that the TX pins remain HI-Z except when they are actually transmitting to reduce the chances of output coupling onto the input especially for short TOF measurements.

    The components already on the basic EVM are there for setting the gain of the LNA on the RX side, and for current limiting on the TX side. These do not have anything to do with impedance matching or reducing ringdown like the components in the switching circuit (described in the post that I linked).

    Regards,