1. ondrej.lufinka@gmail.com

    Thread Starter New Member

    Jun 17, 2013
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    Hello,

    I am trying to built a h-bridge structure to amplify twice the signal for buzzer. Structure of the circuit is similar to one on the picture. Buzzer is connected between C1+ and C1-. Just the types of tranzistors I need different.

    [​IMG]

    So the differencies are: I use +4V as supply voltage and also input signals are squares from 0 to +4V. The inputs are set so on the output between C1+ and C1- should be signal from -4V to +4V (switching between upper left + lower right open / upper right + lower left open). For that I need to use PMOS transistors in depletion mode in the upper half (to be closed at +4V input and opend at 0V) that can supply "strong" "1" on the output. And NMOS transistors in enhancement mode in the lower half (to be closed at 0V input and opened at +4V) that can supply "strong" "0".

    My question is just about what transistors to use? NMOS are not problem. But I have crazy difficulties in searching for those PMOS in depletion mode. Does anybody have some suggestion for part numbers? Or is there maybe some component that integrates whole h-bridge CMOS structure? Note: I really need that depletion mode. That's my biggest problem in searching.

    Thank you for help!
    Ondrej
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    488
    What you are describing is an enhancement mode. At 0V Vgs there is no conduction channel.

    There are tons of enhancement mode pmos devices available.

    Will you be working with +-4V or 8V or 4V in total? It's not exactly clear.
     
  3. ondrej.lufinka@gmail.com

    Thread Starter New Member

    Jun 17, 2013
    4
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    Thanks for reply!

    Sorry i havent described properly..
    Here is the link that explains better: link
    Just for the supply voltage I need +4V and input for tranzistors is squared signal from 0 to +4V lets say at 4kHz. For those two inputs there is 180° delay.

    Are you sure PMOS in enhancement mode are enough for the upper half? Because I need them to open at 0 not at for example -2V..

    Ondrej
     
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Please post the buzzers spec sheet.
     
  5. ondrej.lufinka@gmail.com

    Thread Starter New Member

    Jun 17, 2013
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  6. ondrej.lufinka@gmail.com

    Thread Starter New Member

    Jun 17, 2013
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    Ok I have finally found one gate that exactly matches my needs. So no necessary to build my own one.. Thanks god. Link: Dual CMOS Inverter

    By the way I have also found (on wikipedia) that PMOS tranzistors with DEPLETION mode are not produced any more in single package. Just integrated in ICs. Im not sure if wikipedia is reliable source but anyway Im glad I dont need to search for them. My buzzer is now working in this configuration:

    Excuse the bad quality :) Just quick drawing.
     
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