Help! uWave xistor bias oscillates!

[Fred Bloggs]

Larry Brasfield wrote:

Simulation is not going to have any bearing on how
inductance varies with plate count and dimensions.

It most certainly does, idiot- the simulation drives the choice of plate
count and dimensions.

Of course, they also take into account their own
production processes and constraints. For low
voltage ceramic caps, uniformity of the dielectric
imposes limits on thickness versus yield. So it
would be naive to think that all ceramic caps of
the same type, size and value are the same just
because cap makers hire competent engineers.

Are you talking to yourself or some other internal demon? That statement
does not seem to be in response to anything I wrote.

Assertion without evidence or argument. I see
no reason to believe that some measurements
are not made from endcap ends, and others made
from endcap sides. Nor do I see any reason to
believe that the effects of such differences cannot
explain the 110 pH difference reported earlier.

As for "frequencies make this ...", that looks like
irrelevant gibberish to me.

You just don't worry yourself about it- let Agilent and the T&E
community work this out. They seem to have gotten along just fine
without your assistance thus far.

[derf] every single one of the test fixture, fixture probing, and reference plane extension effects has been characterized
accurately and the impedance analyzer provides for their correction.


It is clear to me that you have missed the point. The
fact that any instrument purports to provide some
kind of correction for fixturing does not eliminate
the definitional issue. The simple fact is that there
is no defined way to partition mutual inductance
between a component and connections to that
component such that a lumped inductance can be
assigned and claimed to belong to the component,
except by fiat.

No- that is bs- they have 4T connections that eliminate fixture mutual
inductance effects- there is no "purporting" to it.

It is not necessary to present simple-minded perfect opens and shorts for calibrations as you suggest.


Amazing that you take my "known (or 0) inductance"
to be perfect anything other than inductance. You are
so desparate to detect ignorance that you invent it.

So says you....

This is obviously a bit academic for normal inductors,
wound to increase internal inductance. But for bits of
metal that resemble a straight conductor, I do not see
a good way of glossing over the issue if one cares to
distinguish 500 pH from 610 pH and claim either to
be right or wrong.

[derf] It is clear you have never used an impedance analyzer in your life.


That makes clear the depth of your delusion. I have
used a variety of impedance analyzers, as well as a
few network analyzers for measuring impedance.

And what drug regimen were you on at the time? Some with hallucination
side effects to be sure....

 

[Joerg]

Hello James,

Not a bad idea when you've got the real estate. I measure
a loose piece of 304 x 80 x 1.5mm (0.062") glass/epoxy
material (presumably FR-4) from my heap at 660pF, or 2.7pF/cm^2.
Using the thinner 0.031" stuff, and situating your island
between solid planes above and below, one could get quadruple
that to about 11pF per cm^2, and cheaply too...,

In your case you could extend the small strips on the DC side of the
inductors to under the caps, under the resistors, in between etc.

Inductors can also be done on FR4. At a few GHz you don't need much and
this way you have the performance under your design control, plus they
cost next to nothing.

What I used to like were embedded beads that follow a stripline pattern.
But they are sometimes frowned upon by PCB mfgs because of the large
drill sizes. Plus you had to place a drop of glue onto them or they'd
rattle. But at a few GHz ferrites aren't so hot, they are just to muffle
any lower frequency noise that could enter.

and if you've got budget, ...

My designs usually are.... so, can't use the fancy stuff.

Regards, Joerg

http://www.analogconsultants.com