Type: Posts; User: dick_freebird

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  1. Closed: Re: Op-amp design specification for certain application

    "Accurate" closed loop gain wants some care, as the
    GBWP is usually the -3dB point - where gain has rolled
    off by 30% or so. That's not "accurate" really. You will
    want some excess GBWP if you...
  2. Replies

    Closed: Re: High Frequency using 8051

    You might just like a large MOSFET gate driver without
    the discrete FETs, depending on the (not-stated) load
    current, rise/fall times and tolerance of the part to
    inductive over / undershoots....
  3. Replies

    Closed: Re: Varactor C-V Curves In Cadence

    I would do a transient analysis with a pulsed current source
    and a trivial shunt (like 1E12 explicit resistor). I=CdV/dt, use
    fixed (after initial condition=0) flat-top I, your C(V) is the ...
  4. Closed: Re: Looking for 'Introduction to CMOS OP-AMPs and Comparators' ebook

    Try, there are many textbooks and semiconductor
    databooks there scanned in and downloadable in many formats.
    The search there works well too; if you don't find what you're
  5. Closed: Re: Analog Layout - Multipliers and Fingers

    Gate resistance is a key concern for RF and very high
    speed drivers.

    Debiasing effects matter at higher currents, if you feed
    one end through skinny metal the far end may not "pull
  6. [SOLVED]Closed: Re: measuring the parasitic capacitance at a certain node in cadence

    If you include adding minor schematic mods, then I prefer
    to add a shunt pulsed current source, who can inject a
    known small charge (large enough to be seen, small enough
    to be small-signal-ish)...
  7. Closed: Re: CMRR is less than the DC differential gain

    Because the DC diff gain is what's giving the CMRR and there
    is always a "hidden tax" - like nodes with positive common
    mode gain, which have to be overcome.

    If you take the open loop diff...
  8. [SOLVED]Closed: Re: Are there relays made for inductive loads

    You need to look carefully at the guts of a SSR. SCR / Triac
    types behave badly with inductive loads (though I have used
    phase-cut dimmers to run series-wound motor tools, neither
    the dimmer nor...
  9. Replies

    Closed: Re: Make component in LTspice

    I'd take the LED .model and scale Vf and Rs by *N (string #),
    as a start. Same for the (Schottky?) diode string. Then one
    diode of each, referring to the customized models, done.
  10. Closed: Re: heat shrink tubing over heat shrink tubing

    I've done this many times for the same reasons. You might
    look at alternatives such as automotive wire-loom and strain
    reliefs; you do not want your soldered lug connectors to be
    the mechanical...
  11. [SOLVED]Closed: Re: Are there relays made for inductive loads

    The desired product is unclear to me.

    AC-coil relays might be a bit funny operated at 140Hz but
    it's not really said, what's the coil drive and what's the
    switched source and load.

  12. Replies

    Closed: Re: gate connection using poly vs metal

    There are good reasons for and against, as the engineer
    the value judgment is up to you.

    For example maybe it's better to route poly in a standard
    cell logic library, than "bake in" metal2...
  13. Closed: Re: Adding a pulsed switch to a dc voltage source in cadence library

    You could consider using poly sources (vcvs) to create Vdd and the "switching input", a (say) 0-1V ramp at one terminal pair for the time varying aspect, a V=3.3 source multipled by the ramp is your...
  14. Replies

    Closed: Re: gate connection using poly vs metal

    There will be a "master" and N "slaves" in the current mirror
    rack and you want to pay attention to where the reference
    current flows. For example if you push the current in at the
    left end of a...
  15. Closed: Re: Searcking for an IC with fast rise time low frequency

    Might get a "clock in a can" oscillator (fixed or VCO) with
    an HCMOS output, and use the fastest AC series gate
    you can find to sharpen up the drive edges. With good
    layout and maybe HC drives...
  16. [SOLVED]Closed: Re: Generating more EMI due to BLDC motor

    Your 63MHz might be winding SRF or some other aspect of
    the harness and electromechanical assembly ringing. Might
    be worth connecting some other load and see if the frequency
    moves (say, another...
  17. Closed: Re: using a crankshaft position sensor to implement electronic ignition

    The modern-ish cars I've worked on have CKP (crankshaft position)
    sensors but this gives you two possibilities for trigger, 0 and 180
    camshaft degrees from where you want. A camshaft sensor ...
  18. Closed: Re: Gm of transistor in hspice when it is called XM

    I have no idea what "xl7" is or is meant to do, but I would
    be looking for something like


    in simulator-appropriate syntax for gm, and plot...
  19. Closed: Re: Misconceptions and flaws noticed by the more educated...


    2) Ohm's law wrongly taught as R=E/I. R=E/I is the definition of resistance, not Ohm's law. A resistance follows Ohm's law if its value is constant over a reasonable...
  20. Closed: Re: Gm of transistor in hspice when it is called XM

    There will me something like XM8^M1 as a device at the bottom
    of it all, which can be probed in the usual way as long as you
    "spell its name right". If you're using a GUI schematic driven
  21. [SOLVED]Closed: Re: can flux from switching inductors cause interference

    We did not like ground planes under the SW node because
    it couples all that trash right into the ground, messes up
    current sense and other ground (which ground?) referred
    signals etc. The SW...
  22. [SOLVED]Closed: Re: can flux from switching inductors cause interference

    Circular sweep trimpots include a "free 3/4 turn inductor
    in every box".

    You could check the hypothesis easily enough by soldering
    in a tight pair of chip resistors of appropriate (to the trim-...
  23. Closed: Re: Misconceptions and flaws noticed by the more educated...

    The larger problem may be in expecting textbooks to teach
    everything. Especially ones written by professors who have
    avoided practical hard-knocks lessons in favor of formulae.

    We are awash in...
  24. Replies

    Closed: Re: Improving efficiency

    I have found it most helpful to concentrate on the "elements
    of inefficiency". Efficiency of the assembly is your report card.
    Inefficiencies are what you quantify and drive down one by
    one, as...
  25. [SOLVED]Closed: Re: can flux from switching inductors cause interference

    Component "failure" is a pretty remote possibility but circuit
    misbehavior is commonplace.

    You can get charge pumping across any junction if there is
    AC activity on the pins. This is a known...
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