Connect with us

oscillator design @24GHz - which transistor

Discussion in 'Electronic Design' started by cubeagree, Mar 31, 2007.

Scroll to continue with content
  1. cubeagree

    cubeagree Guest

    Hi, I want to design an oscillator working at 24GHz - output power
    approx. 10dBm - but I want to use a discrete transistor (pHEMT) in a
    housing which can be hand-soldered. Until now I have found only 2-3
    transitors which are specified, i.e. at least s-parameters are
    available @24GHz.
    Does anybody can help me to choose the right transistor - any hints
    are welcome. Thanks !
     

  2. You should select a transistor that is somewhat
    faster, choose one that makes 45 GHz or more.
    There is BFP520 with an Ft of 45GHz and the
    BFP620 with an Ft of 65GHz, both NPN bipolars
    in SOT cases though.

    Tuneable ?

    Rene
     
  3. John  Larkin

    John Larkin Guest

    Checked the NEC phemts?

    What sort of resonator did you have in mind?

    John
     
  4. cubeagree

    cubeagree Guest

    Hi John,hi Rene

    thanks for the quick answer - for the Infineon npn-transistors I
    didn't find any data above 6 GHz.
    The resonator will be a microstrip parallel feedback resonator - no
    DRO because of difficulties in positioning in mass production and cost
    issues.
    The pHEMT transitors from NEC I have already checked and I think they
    are quite good, I also found some from Mitsubishi and NEC, but I am
    not sure whether there are any others ? So if somebody has already
    designed a transistor ocillator with discrete transitors - please let
    me know what kind of transistor did you use.

    Thanks a lot.

    Peter
     
  5. cubeagree

    cubeagree Guest

    Hi John,hi Rene

    thanks for the quick answer - for the Infineon npn-transistors I
    didn't find any data above 6 GHz.
    The resonator will be a microstrip parallel feedback resonator - no
    DRO because of difficulties in positioning in mass production and cost
    issues.
    The pHEMT transitors from NEC I have already checked and I think they
    are quite good, I also found some from Mitsubishi and NEC, but I am
    not sure whether there are any others ? So if somebody has already
    designed a transistor ocillator with discrete transitors - please let
    me know what kind of transistor did you use.

    Thanks a lot.

    Peter
     
  6. colin

    colin Guest

    Not very close but I made a 1-2ghz vco with a PHEMT JFET I got from ebay,
    unfortunatly havnt got the part no. to hand atm,
    but the device marking is 'D' so its probably got a very long number.
    It was just a delay line type feedback curtuit,
    It was quite a high freq device and probably still has enough gain to
    oscillate at that frequency,
    although ive no way of testing at anywhere near that, sounds interesting.

    Colin =^.^=
     
  7. cubeagree

    cubeagree Guest

    Hi Colin,

    this sounds interesting - I would be very glad if you can find out the
    name of the transitor.
    Thanks for your help.

    Peter
     
  8. John  Larkin

    John Larkin Guest

    I've never tried to go that fast, but it seems to me that a bipolar
    with a 45 Ghz Ft only has a beta of 2 at your frequency, which doesn't
    bode well for making a good oscillator. A phemt would seem a better
    choice to me.

    John
     
  9. colin

    colin Guest

    managed to find it eventually, my disc got corupted
    NE32584C

    its got specs upto20ghz

    even got a model upto 18ghz

    posibly got >9db of gain at 24ghz



    Colin =^.^=
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-