Can one 1uF ceramic replace a combined 1uF tant + 10nF for bypassing ?

"Adam S"

Any day you can avoid using a tantalum cap is a good day.

....... Phil

Why dont you put some "accurate" spice models of the manufacturers capcitors in to a Spice simulator and see how they react to transient and frequency inputs.

Here! Yageo have the spice models and simulator.

JG

"above resonances"? A capacitor is an inductor above resonance, so any plots up there are rather useless. Also misleading, as the resonant frequency is going to be different in your circuit than in any other, or test, circuit.

I'd make up a little test jig, with a noisy IC, say a 74F161 toggling at 50MHz, a HF scope to BNC coax line soldered right to pins 7 and 14, and various capacitors I can plonk onto those pins.

"Ancient_Hacker"

...... Phil

Not so... in many cases operating capacitors above their self-resonant frequency is useful.

This is true for pretty much any simulation vs. a built-up PCB; the devil is always in how much the difference is.

Pls answer these questions:

(1) In a series LC circuit, below resonance the reactance is: ( capacitive, resistive, inductive )

(2) At resonance the reactance is: ( capacitive, resistive, inductive )

(3) At above resonance the reactance is: ( capacitive, resistive, inductive )

(4) If you want a capacitor, use a ( capacitor, resistor, inductor )

(5) If you use an inductor in place of a capacitor, you are a: (winner, drone, loser )

The obvious answer being to use an inductor above its SFR :-)

Uh, won't there be the slightest amount of leakage at dc?

Haw!

Actually, I glommed onto a bunch of "Genoformers" which curiously measured as capacitors on my LC bridge at 1000 Hz. Turned out they were transformers designed to pass seismic signals, so 1000Hz was way above their SRF.

Capacitor. However, once you get past EE 101 designs, you find that there are plenty of cases where you can't get a single capacitor that behaves reasonably close to an ideal capacitor over the design's intended operating range.

Having to with deal with the reality of doing more complex designs than you do?

Interested in testing out a gyrator?

Hear hear.

I had to do a very systematic approach to a number of InfiniBand boards I designed. Without going into detail, let's just say there were a _lot_ of frequencies of interest that had to be appropriately decoupled.

No one size or type of cap will span the decoupling requirements on a reasonably complex board; one chooses various caps to implement specific parts of the decoupling requirements. I also used some inductors, of course - there are times for them; and all that doesn't incude the power system ;)

Cheers

PeteS

"Ancient_Hacker"

( snip all the asinine drivel)

???????????

........ Phil

Have you bonked Lyn(n) yet?

DNA

I won't call that leakage, but I think I added a smiley :-) Here's another one :-)