How to get value of required drive current

Discussion in 'General Electronics Chat' started by eefocus, Sep 6, 2012.

  1. eefocus

    Thread Starter New Member

    Sep 6, 2012
    6
    0
    Hello everyone,I am working on a project of a transmitter.The major part is to generate short pulses.The only source is an oscillator.
    However,to choose the proper oscillator,I need to know how much current is needed for the downstream circuit.So I simulate it in Agilent's ADS using transient simulation just like Spice.
    The results show that different output impedances of oscillator lead to different currents in circuit. For a given output impedance,I wonder if the drive current can be lower and still make circuit work.Because many practical oscillator does not have so big drive current(for 20ohm,it needs 70mA).

    So my question is how to get the drive current that is needed.Is that exactly what Spice show you?How can I know whether a device with a less drive current or power(voltage remains the same) can still work or not?

    I still do not know how to limit the max current of circuit or power of source in Spice.Is there power source?

    Thanks!
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    The usual request. Post a schematic of the circuit.
     
  3. eefocus

    Thread Starter New Member

    Sep 6, 2012
    6
    0
    [​IMG]
    The last part is a short transmission line.The 2-diode is a Schottky diode,another is a step recovery diode.
    This is a schematic of ADS.
     
    Last edited: Sep 6, 2012
  4. eefocus

    Thread Starter New Member

    Sep 6, 2012
    6
    0
    [​IMG]
     
  5. eefocus

    Thread Starter New Member

    Sep 6, 2012
    6
    0
    Noone replys?
     
  6. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    150 GHz is not exactly hobbyist territory. Do you expect individuals to be familiar with the tools and techniques required for this kind of work?
     
  7. vk6zgo

    Active Member

    Jul 21, 2012
    677
    85
    I'm sorry,but it doesn't make sense.
    Is TLSC on the right hand side an150GHz RF module which you are trying to power from the pulse generated at the LHS?

    If so,this is not how it is done.
    The module (if that is what it is),must have its own power supply,with the pulse just turning the RF on,but not supplying operating power.
    I feel you don't know enough about what you wish to achieve for your simulation to mean anything.
     
  8. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    The lack of active stages was a bit puzzling. vk6zgo pointing out the presence of a potential module makes sense. So what is in between is some kind of "matching" or "steering" logic -- I guess. As he pointed out it still doesn't make any sense at least to me.
     
  9. eefocus

    Thread Starter New Member

    Sep 6, 2012
    6
    0
    TLSC is just a short transmission line which used to reflect the half pulse to get the full cycle of a pulse.The 150GHz just means the transmission time is 1/150e9=6.6e-12s.It does not need any power,just a section of line.


     
  10. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    Looks like you're pretty far away from making an actual transmitter, and I don't see why you need to do what you are doing to make one.
     
Loading...