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Type: Posts; User: BigBoss

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  1. Replies
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    Closed: Re: BJT V(ce) ON in common emitter mode

    The solution comes into my mind is Darlington Transistor with Low Vce(sat) feature.. Am I wrong ??
    Or using a simply a MOS ?? Zero bias current and very low sat voltage ..
    I'm still not sure what...
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    Closed: Re: BJT V(ce) ON in common emitter mode

    -Ib has to be <4mA
    -Vce(sat) has to be >0.5V @ Ic=40mA..

    I wonder what type of application is it ?? If you would Vce(sat)>0.5V, connect simply a resistor ??
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    Closed: Re: bfq162 pnp comlementary?

    This type of case and transistors are gone.. Even you find a complementary, it will not have exact specifications..
    What is your project, I can make an alternative offer
  4. Closed: Re: Which transistor need to be chosen for designing KU-Band LNA Design high gain, lo

    You don't have too much choice..
    http://www.cel.com/product.do?command=viewSelector&group=4#a3530
  5. Closed: Re: High power efficiency oscillator topologies?

    It's normal because you touch most sensitive node of the oscillator.I suggest you to use Emitter Follower Buffer to isolate the load and oscillator because even if you use high impedance node as a...
  6. Closed: Re: High power efficiency oscillator topologies?

    If you have already found a D-Class Differential Low Power Oscillator as you wish, use only one output and make the second one grounded via a capacitor.
    Since the oscillator will not be loaded by a...
  7. Closed: Re: Pulse transformer output measured vs. calculated?

    OK, if you are able to measure primary and secondary side of the transformer independently, you can use a "Lossy Transformer Model" that can be found in the literature and use it in LTSpice...
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    Closed: Re: Metal patterns in PCBs

    They are just to connect a SMD component where the matching is proper.The designer may make a fine tuning to shift left and right the matching component.
    There are also stub optional pads around...
  9. Closed: Re: High power efficiency oscillator topologies?

    What is the frequency and what is your target ??
  10. Closed: Re: Pulse transformer output measured vs. calculated?

    I suggest you extract a accurate model of the Pulse Transformer ( it might be simple or complex) then use a simulator because calculating Voltages and Currents of such a circuit will be very...
  11. Closed: Re: Looking for a VHF/UHF 90 degrees Hybrid Coupler part

    www.werlatone.com

    They have wideband hybrids but I think they are expensive ..
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    Closed: Re: Problem about amplifier biasing circuit

    In order to expand The Voltage Headroom.If we use a Resistor, we'll loose Voltage Headroom..
    RFC can sometimes be a part of Matching Circuit moreover even Bonding Wires are also be used for Matching...
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    Closed: Re: Metal patterns in PCBs

    No..It's a pattern to tune the Matching Circuit.
  14. Closed: Re: Pulse transformer output measured vs. calculated?

    While calculating Voltages and Currents with Pulse Transformer, how did you model it ?? Because Ohm's Law cannot be applied to Transient Domain in which is your case.
    I mean, you cannot find...
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    Closed: Re: Problem about amplifier biasing circuit

    Ld can be used either Matching Purpose or RFC.Depends on the Designer..
    But if this LNA is a RFIC type Matching is not very necessary due to very short distances in RFIC, Ld in this case might be RF...
  16. Closed: Re: Looking for a VHF/UHF 90 degrees Hybrid Coupler part

    It will probably exceed.Therefore I'm saying it's more difficult to find Low Frequency Passive Components rather than High Frequency ones.
    In fact the Bandwidth can be extended by using...
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    Closed: Re: Power Amplifier Design

    You should drive the PA until the PA enters into SAT mode in order to observe the Efficiency in Main and Aux. Amplifier regions. Back-Off effect in Efficiency can be observed with this method ..
  18. Closed: Re: Looking for a VHF/UHF 90 degrees Hybrid Coupler part

    The Bandwidth is more than 2 Octaves at Low Frequencies, it's pretty difficult to find it within specifications.
    It's easy to find a Hybrid Coupler at High Frequencies with a bandwidth more than 2...
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    Closed: Re: Power Amplifier Design

    Output Power should be vicinity of P1dB. In fact, there isn't any convention about that because some manufacturers use P3dB some of them P1dB.
    Nevertheless, P1dB Compression Point is chosen and...
  20. Closed: Re: crosscoupled VCO in keysight ADS

    Small signal Models are NOT used neither in Transient nor HB analysis.
    You have to read "fundamentals of simulation techniques" from different tutorials/app. notes.
  21. Closed: Re: How to increase high frequency output power

    It depends on many variables.It's not easy to say..
    Output Power may be function of Power Gain, Load,Transistor (Amplifier/Active Device ) itself,Matching,Parasitic Elements,Package, etc.
    If I...
  22. Closed: Re: problem: coupling coefficient for two hairpin resonators

    I think the results of that textbook in fig 8.16 are theoretical or analytical not EM simulated.Otherwise the peaks cannot be so sharp in practical world.
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    Closed: Re: Mosfet Driver Vs BJT Driver

    The MOS Input Capacitance 8nF (max)!! It's really huge if the PWM frequency is relatively high.It will need a "strong" Driver for it.
  24. Closed: Re: problem: coupling coefficient for two hairpin resonators

    I have simulated that resonator in AXIEM and found that the resonator coupling gap has reverse effect compare to standard ones.
    154939154940154941
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    Closed: Re: Mosfet Driver Vs BJT Driver

    It's not necessary this circuit.If the Fanout Capacity of the PWM Source sufficient, you can directly drive the MOS if the signal swings between 0-5V..
    Otherwise use a simple Buffer from any mfg.
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