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Which university produces good analog EEs?

Discussion in 'Electronic Design' started by Joerg, Sep 25, 2007.

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  1. Guest

    Micropower bandgaps show up in really mundane areas of chip design
    nowadays, such as POR. Really overkill, but because customers know it
    can be done, they expect it to be done. If you reverse engineer Maxim
    chips, you'll find a bandgap comparator circuit in the POR. Plenty of
    patents on such circuits, but never litigated to my knowledge. They do
    save power since the bandgap and comparator are folded into one
    circuit.

    One of the trickier micropower circuits are those in thermal shutdown.
    That is where leakage can really kill you, so parasitics are required.
    However, it isn't exactly rocket science.

    BTW, I forgot to mention it, but UCLA has a fair amount of analog
    design classes. Lastly, there is the Swiss Federal Institute of
    Technology (or close to that). They have all sorts of papers on
    dynamic biasing scheme, i.e. schemes to make micropower op amps slew
    quickly by boosting tail current, etc.
     
  2. Guest

    Eh, maybe they just wanted a trip to Silicon Valley. I was amazed at
    the number of MIT grads that had logic design on their resumes, but
    didn't know how to draw basic mos logic gates. It turns out they
    studied computer architecture with silicon compilation to get to the
    end product. That just doesn't fly on small mixed mode chips where the
    logic is implemented in rather coarse mos technology.
     
  3. JosephKK

    JosephKK Guest

    Joerg posted to
    sci.electronics.design:
    Ah but they do. High voltage (over 1000 V) vacuum tubes still
    popular. I think Win even used a tube solution for a 10kV ramp
    generator recently.
     
  4. Tim Williams

    Tim Williams Guest

    That was the one.

    Tim
     
  5. Joerg

    Joerg Guest


    Who? There are some tube mfgs and probably the largest ones are Sovtek
    and Svetlana but there ain't much in HV tubes there. It's all audio
    because that is where the big bucks can be made.

    IIRC he opted for a FET stack.
     
  6. Joerg

    Joerg Guest


    Micropower bandgaps show up in really mundane areas of chip design
    nowadays, such as POR. Really overkill, but because customers know it
    can be done, they expect it to be done. If you reverse engineer Maxim
    chips, you'll find a bandgap comparator circuit in the POR. Plenty of
    patents on such circuits, but never litigated to my knowledge. They do
    save power since the bandgap and comparator are folded into one
    circuit.
    [/QUOTE]

    Yes, on chips this is no problem but no company has marketed those
    individually at a decent price. Meaning the sub-10uA references are
    usually not very suitable for mass production because you can't have a
    reference in there that costs more than all the rest of the board. So we
    have to use tricks such as pulsing and storing.

    One reason why POR/BOR circuits contain precise references is that the
    chips they are on need it elsewhere as well. For example, a uC with an
    ADC on board. The often touted "cheat reference" consisting of four
    equal resistors hung onto the rail doesn't cut the mustard.

    We didn't have much luck with UCLA so far. They didn't understand my
    module specs and couldn't even solder. Had to let them go. Europe would
    be an option but the immigration procedure is a real hassle. Plus there
    will be an expensive international move required unless you catch them
    right after their degree. Europe doesn't have such an extreme shortage
    of analog guys because larger companies there are often foolish. Some of
    them consider anyone over 40 a geezer that needs to be replaced by a
    kid. The consequences are very visible, for example with NXP's web site.
     
  7. ....and some really nice HF RF linear power amplifier devices.

    Jim
     
  8. Joerg

    Joerg Guest

    Ok, yeah, of course you can still get some of the really big tubes. But
    those aren't practical and economical for a small HV circuit while the
    old TV ballast triode might have been.
     

  9. http://broadcast.rell.com/tubes.asp


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  10. JosephKK

    JosephKK Guest

    Joerg posted to
    sci.electronics.design:
    I am asking him.
     
  11. Guest

    POR really should reflect what it takes to make the chip fly, not
    necessarily some arbitrary specification. That is, logic needs at
    least a VT, the worse case of N or P. So generally a chip POR will
    have a circuit that insures you at least have enough juice to turn on
    your worse case fet. Once you trust the logic (well, at least under
    static conditions), the next step is to insure the bandgap is awake,
    generally an output something above a VTN. Throw in a timer and
    hysteresis to make sure the supply rail hasn't sagged. Stuff like
    that. Thus POR is process and temperature dependent. However, as you
    probably know, that doesn't give the customer the warm and fuzzy
    feeling. They want to see something nice and snappy that can be
    verified with a DVM.
     
  12. Guest

    Oh yeah, the lack of soldering skills. That would require the student
    to have actually built something. These younguns just know how to
    program. You've seen the posts where a pic uP is the solutions to any
    task, not a state machine comprised of memory elements and
    combinational logic.
     
  13. Joerg

    Joerg Guest

  14. Jim Thompson

    Jim Thompson Guest

    Indeed. My latest POR had hysteresis of 3.5VT/3VT plus a delay to
    ensure it held "resetbar" down long enough.

    POR was used only on the digital sections... analog functioned on a
    "bandgap ready" signal.

    ...Jim Thompson
     
  15. Joerg

    Joerg Guest

    Yes, on chips this is no problem but no company has marketed those
    individually at a decent price. Meaning the sub-10uA references are
    usually not very suitable for mass production because you can't have a
    reference in there that costs more than all the rest of the board. So we
    have to use tricks such as pulsing and storing.

    One reason why POR/BOR circuits contain precise references is that the
    chips they are on need it elsewhere as well. For example, a uC with an
    ADC on board. The often touted "cheat reference" consisting of four
    equal resistors hung onto the rail doesn't cut the mustard.

    We didn't have much luck with UCLA so far. They didn't understand my
    module specs and couldn't even solder. Had to let them go. Europe would
    be an option but the immigration procedure is a real hassle. Plus there
    will be an expensive international move required unless you catch them
    right after their degree. Europe doesn't have such an extreme shortage
    of analog guys because larger companies there are often foolish. Some of
    them consider anyone over 40 a geezer that needs to be replaced by a
    kid. The consequences are very visible, for example with NXP's web site.
    [/QUOTE]


    POR really should reflect what it takes to make the chip fly, not
    necessarily some arbitrary specification. That is, logic needs at
    least a VT, the worse case of N or P. So generally a chip POR will
    have a circuit that insures you at least have enough juice to turn on
    your worse case fet. Once you trust the logic (well, at least under
    static conditions), the next step is to insure the bandgap is awake,
    generally an output something above a VTN. Throw in a timer and
    hysteresis to make sure the supply rail hasn't sagged. Stuff like
    that. Thus POR is process and temperature dependent. However, as you
    probably know, that doesn't give the customer the warm and fuzzy
    feeling. They want to see something nice and snappy that can be
    verified with a DVM.
    [/QUOTE]

    The customer won't even be able to hold a DVM to it if on-chip. What
    customers like me really want to see is a POR plus BOR where brown-outs
    are handled properly. Anything less than that is a risk. For some reason
    it usually takes the uC folks years to figure that out, no idea what
    they find so difficult about it.
     
  16. Joerg

    Joerg Guest

    Yes, on chips this is no problem but no company has marketed those
    individually at a decent price. Meaning the sub-10uA references are
    usually not very suitable for mass production because you can't have a
    reference in there that costs more than all the rest of the board. So we
    have to use tricks such as pulsing and storing.

    One reason why POR/BOR circuits contain precise references is that the
    chips they are on need it elsewhere as well. For example, a uC with an
    ADC on board. The often touted "cheat reference" consisting of four
    equal resistors hung onto the rail doesn't cut the mustard.

    We didn't have much luck with UCLA so far. They didn't understand my
    module specs and couldn't even solder. Had to let them go. Europe would
    be an option but the immigration procedure is a real hassle. Plus there
    will be an expensive international move required unless you catch them
    right after their degree. Europe doesn't have such an extreme shortage
    of analog guys because larger companies there are often foolish. Some of
    them consider anyone over 40 a geezer that needs to be replaced by a
    kid. The consequences are very visible, for example with NXP's web site.
    [/QUOTE]


    Oh yeah, the lack of soldering skills. That would require the student
    to have actually built something. These younguns just know how to
    program. You've seen the posts where a pic uP is the solutions to any
    task, not a state machine comprised of memory elements and
    combinational logic.
    [/QUOTE]

    There were elaborate uC solutions I found in my career that I have
    replaced with 20-30 cents worth of logic chips and some diodes. This
    "TV-dinner" behavior already started with the advent of PALs. Almost
    everyone was jumping on them (except me ...) and they were wasting lots
    of power. And money.
     

  17. Some of the HV stuff is still being made in small runs.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  18. John Larkin

    John Larkin Guest

    Cute trick: use an HV rectifier, like a 1B3, and control its filament
    voltage to make it an amplifier. I used to do that when I was a kid...
    flashlight battery, rheostat to filament (with long plastic shaft!),
    neon sign transformer, charging a bank of oil caps, with the loop
    closed manually. You could run the xenon flashtubes just below the
    point where they'd fire spontaneously.

    Amazing I'm still alive.

    John
     

  19. One TV tech I worked with when I was 13 would reach into those old
    tube type color TV sets and grab the second anode lead, then touch
    someone. ONCE. Most people never got close to him again, after that.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  20. krw

    krw Guest

    I worked in P'ok for 19 years. Great place to be *from*.
    From there, we moved North 200 miles but looking to get out for
    somewhat warmer climes now (the instant the house sells). The
    Winters do suck and it looks like we'll be there one more. :-(
     
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