Matrox, a liar? [NOT my comment, but the site's]

[Greebe]

@Marshmallowman

equivalent filter circuits can made with either components, a fifth order filter is a fifth order filter whether you use inductors,capictors or a combination of both..

Sorry guy but that is totally incorrect. A fith order filter network consists of a RCL components (Resistor, Capacitor, Inductor) and cannot be made from just caps or inductors interchangeable by themselves.

Seeing that this nit site claims Matrox is lying is a joke in itself. M simply changed vendors (cost analysis) so the parts look different but the values remain the same. I say let them eat hat (clueless noroms)

[UberLord]

For the clueless here could someone explain what a 5th order filter is and does?

TIA

[Flyke]

The vendor issue sounds right to me.

It is quite common during beta production to produce home-made inductors and once final production is reached you have the inductors produced out of the house.

Regarding what a 5th order filter does..

We are talking lowpass, that means frequencies above a certain cut-off frequency are filtered out.
Ideally any frequency above a threshold will be gone in the filtered signal - but this is not an ideal world and frequencies above the threshold will just be attenuated, the higher the frequency the more attenuation.
The order of a filter determines how steep the cut-off is, the higher order we have the better it attenuates frequencies above the threshold.
The picture below should illustrate the idea of higher order filters.
The higher the number on the graph the higher order.



Hope it helps those who are curious

/Flyke

[SteveC]

UberLord - if that went right over your head, then think of a low order (1 or 2) filter as being crap - instead of a brick wall (blocking absolutley any frequencies below or above a set frequency), it's a play-dough soft squishy wall letting anything 'near enough' past (in graphics terms, causing blurry screens!). As you increase the order of the filter, more and more components (resistors, capacitors and inductors) are used to improve the performance of the filter. The higher order filters toughen up the play-dough into hard rubber and so it acts a lot more like a brick wall filter.

So, in a bandpass filter, instead of:

      _____
     /     \
____/       \_____

(low order, nVidia)


     __________
    |          |
____|          |_______

High order, Matrox

Remember it's impossible to acheive perfection in filter design.

[rylan]

Actually after looking at the pictures, the white chips on the Lx pads are inductors.. I use them at work for power supply regulation. what it looks like is the inductors int he prototype are actually wire-wound inductors, while the white ones are the mass-produced chip package inductors.. remember that low value inductors don't have to have wires wrapped around.. and infact those types are used more for low-frequency filtering than energy storage (hence the high order filter comment by Matrox). They work by having a high impedance at low frequencies, and zero impedance at higher frequencies... tho there are all differant types.

Oh, afterburn and SteveC you are correct, you cannot replace a capacitor for an inductor. Electrically inductors are like a short, and capacitors are open.. you place an inductor in series with a signal, while a capacitor goes from the signal to ground. So if you tossed caps in there, you'd get no output :P

[Marshmallowman]

Greebe you are right, you can't just swap components.

what I was trying to say is that equivalent filters can't be made in a multitude of ways, saying that they look different means nothing because they may well produces the same filtering characteristics.

typicaly if you make a circuit with an RC filter or an RL circuit they will have a lower Q of RLC circuit but filtering must be "tuned" to get the desired output wave, the sharpest response is not always best in all parts of the circuit. otherwise you can nasty overshoots in the wave form (ala nv)

I am wondering if the new one may possibley better than the old one?.

pity I can't read the page, but calling matrox a liar is just ridiculous!, it still is a fifth order filter!.

[Greebe]

Well then we also have all sorts of different types of 5th order filters. Eliptical, Bessel, Chebyshev (etc) beyond your typical butterworth filter design. Bessel and especially Chebyshev designs improve (reduce) ringing and or phase shifts induced while improving the elbow of the cutoff points giving you what Matrox claims, a nice clean output

[Marshmallowman]

[UberLord]

Originally posted by SteveC
UberLord - if that went right over your head

You're right - it did!

, then think of a low order (1 or 2) filter as being crap - instead of a brick wall (blocking absolutley any frequencies below or above a set frequency), it's a play-dough soft squishy wall letting anything 'near enough' past (in graphics terms, causing blurry screens!). As you increase the order of the filter, more and more components (resistors, capacitors and inductors) are used to improve the performance of the filter. The higher order filters toughen up the play-dough into hard rubber and so it acts a lot more like a brick wall filter.

Now I understand!

Thanks

[mutz]

......facinating!

This long thread over what was probably an obscure attempt to discredit Matrox.

About thirty years ago Mercedes attempted to discredit BMW by spreading rumours that BMW's independent wheel suspension was unsafe and would wear out faster.

...but thanks for the thread. Always good to learn something and bewonder the intelligence and ingenuity of Matrox users.