bandpass filter

ass with

elay

t; it is critical

the patented circuit "destroys" the effect you're looking for.

. You shouldn't have to stagger if you get it right.

ucing the double humped amplitude response. What is unclear for an all pas sive circuit is how they can be coupled and still provide the "second" reso nator having a resistor in series with it. There may be some way of tappin g, but it isn't obvious to me (yet).

nator is missing in (7) for example. I would have to go through it in deta il and see if there is a gain-less form of those equations that can be synt hesized into a network.

I am starting to question this patent. It is crap as far as a BPF goes. Q cir=0.734. It is looking mainly like a heavily overcoupled BPF (there is a 6 dB center dip). I'm not sure there was patentable magic in there, but that question no longer matters.

I did a narrower (than the patent) passive version that was also over-coupl ed to the point of 6-dB of ripple. The phase also flattens some towards th e middle. Perhaps the over-coupling simply "pushes" the gradients towards the edges.

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The following includes the prior passive over-coupled LC. It also includes a conceptual PD shelving circuit that flattens the mid-band shift a bit mo re.

More PD's would flatten it more than the single PD. The PD's also destroy the high-side rejection. (This is why I started with a 1-5 DC-inf pole dis tribution in the passive circuit.)

Again, the PD's are only conceptual. It is yours' now.

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SYMATTR Value 305.940513p SYMATTR SpiceLine Rpar=1G SYMBOL cap 784 -528 R0 SYMATTR InstName C5 SYMATTR Value 1.820912pF SYMATTR SpiceLine Rpar=1G SYMBOL cap 1744 -688 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 59.330671pF SYMATTR SpiceLine Rpar=1G SYMBOL cap 1072 -576 R0 SYMATTR InstName C6 SYMATTR Value 36.057002p SYMATTR SpiceLine Rpar=1G SYMBOL cap 1328 -576 R0 SYMATTR InstName C7 SYMATTR Value 36.057002p SYMATTR SpiceLine Rpar=1G SYMBOL cap 1600 -528 R0 SYMATTR InstName C8 SYMATTR Value 1.820912pF SYMATTR SpiceLine Rpar=1G SYMBOL cap 1792 -544 R0 SYMATTR InstName C9 SYMATTR Value 305.940513p SYMATTR SpiceLine Rpar=1G SYMBOL res 2000 -560 R0 SYMATTR InstName R_load1 SYMATTR Value {Rload00} SYMBOL e 3072 -656 R0 SYMATTR InstName E1 SYMATTR Value 1Meg SYMBOL res 3296 -496 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 1e3 SYMBOL cap 2800 -496 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C10 SYMATTR Value 10e-12 SYMBOL e 3072 -1040 R0 SYMATTR InstName E2 SYMATTR Value 1Meg SYMBOL res 3296 -880 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 1 SYMBOL res 2816 -880 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 1 SYMBOL e 3824 -800 R0 SYMATTR InstName E3 SYMATTR Value 1Meg SYMBOL res 3680 -880 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R4 SYMATTR Value 1 SYMBOL res 3680 -704 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 1 SYMBOL res 4000 -640 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R6 SYMATTR Value 1 SYMBOL cap 3280 -400 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C11 SYMATTR Value .1e-12 SYMBOL e 2320 -704 R0 SYMATTR InstName E4 SYMATTR Value 1Meg SYMBOL e 5008 -512 R0 SYMATTR InstName E5 SYMATTR Value {IL} SYMBOL res 5088 -528 R0 SYMATTR InstName R7 SYMATTR Value 1G TEXT -200 -976 Left 2 !.ac oct 1000 5Meg 15Meg TEXT -1312 -2784 Left 2 ;o TEXT 5416 1528 Left 2 ;o TEXT 504 -1064 Left 2 !.net I(R_load00) Vsrc00 ; Rsrc & R_load determined from Vsrc and R_load TEXT -200 -864 Left 2 !.SAVE S11(vsrc00) S21(vsrc00) S12(vsrc00) S22(vsrc00 ) V(IL_adj) TEXT 504 -1152 Left 2 !.param Rsrc00 = 50 TEXT 504 -1112 Left 2 !.param Rload00 = 50 TEXT 1008 -848 Left 2 ;10 uH is SMRF2007-102M (Gowanda)\nwould need to be t uned TEXT 4904 -280 Left 2 !.param IL_dB = -1.65389 TEXT 4904 -232 Left 2 !.param IL = {10**(IL_dB/20)} LINE Normal -32 -1408 -32 -1408 LINE Normal -32 -1408 -32 -1408

I'd have to design the actual filter, which takes research about standard values, tolerances, available parts, all that grunt work. I'm thinking that the main Ls and Cs would be the same values, 1 or 2% parts off the same reel, and then use two smaller caps to set the final frequencies of both resonators. Arithmetic and grunt work.

I posted numbers. They are neither important nor interesting.

The interesting issue here was whether it is even possible to build a bandpass filter with a flat or reversed phase shift region near the center. That involved stuff like network theory, group delay, thermodynamics, and causality. What Ls and Cs I eventually use at 40 KHz is trivial.

Bwahahahahahaha >:-} ...Jim Thompson

Just trying to educate... and hope that the masses will think problems thru rather than buy the BS... but I doubt it :-( ...Jim Thompson

I noticed the "µ" does some damage in pasted text when reopening in LTSPI CE. The inductor values require patching.

On Tue, 06 Aug 2013 14:17:53 -0700, John Larkin wrote:

This works too. Turns out the the resonators don't need to be coupled, so it's easy to do with active filters, too.

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The killer for impedance control is the board thickness, i.e. space between trace and ground plane.

I gather you don't know what a dummy device is based on your reply. There are things you can do to control the CDs.

Search for INF4420_03_Layout_Print.pdf

See page 57 to see dummy devices used to improve lithography.

For a trace on a PCB, the philosophy is the manufacturer has tuned the process for metal, then space, then metal, etc. That is, the critical dimension (CD) of the process is based on such a pattern. If you don't put the dummy strip in, then the etching is not based on the target CD pattern.

When Cadence (Dracula back then) was first on the market, they went crazy with all these dummy devices. They never saw dummies, since it is something only done for analog.

I build picosecond electronics on FR4 and it works, almost always the first try.

And I do it without violating any of the laws of thermodynamics.

miso is almost always out to lunch.

But, this time, miso is 100% on target.

You _don't_know_ what a dummy device is, do you ?:-)

You should learn. Might help your "picosecond electronics".

Beware the snark because it is manic-depressive >:-} ...Jim Thompson

I failed to point out...

the effective "Q" of this PLL "bandpass" is only 5, since I wanted it to finish simulation (reach equilibrium) before filling my hard-drive with data.

With an equivalent Q of 50 it will retrieve a clock buried in far more nasty noise.

Try it some time. The first time I observed this (nearly 50 years ago) I was astonished! ...Jim Thompson

You snip everything, so I can never tell who or what you are replying to.

--

John Larkin Highland Technology Inc

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

The first time I made a PLL lock to a signal buried in noise was also about 40 years ago, but I wasn't astonished because I expected it. I was of course a lot younger than you at the time.

A PLL and a lock-in and a bandpass filter and a radio are all about the same, give or take a few dB. I still want a bandpass filter ahead of my PLL.

I was around 23 years old. And I don't think Gardner's first edition had even been published yet (my second edition is copyrighted 1979). Yep. I was astonished. And delighted.

Of course you're still a "lot younger" than me (but pushing old age yourself ;-) but, in spite of your age and "wisdom", you still pose causality-defying questions like...

"Is there a form of bandpass filter that has no phase shift vs frequency around the center of its pass-band?"

Go ahead, if it makes you feel good >:-}

I did suggest that a low-Q one ahead of the PLL would be helpful to minimize noise, in an earlier post. (And won't screw up the phase... the wider the BW the softer the phase slope.) ...Jim Thompson

dBm in case one. dB in the latter.

The operational characteristics of the PLL itself should be all that would be needed (or matter) as to determine whether such filtration would be needed (or matter). It can lock, or it cannot. There is no 'try'.

In such a case, the criterion defining the quality of "the lock" (read PLL) should be all that matters. Let the downstream circuitry have the entire spectrum and handle it, if possible. You never know what might be lurking near or embedded in the noise floor. Lots of nice, random numbers down there... :-)

I posted a couple of Spice files for filters that do exactly what I described. Zero phase shift midband and +- adjustable phase/frequency slope about that point by tuning one or two resistors.

A network with a wiggly phase-versus-frequency curve doesn't defy causality. You never talk about conservation of energy or thermodynamics of causality - you're just parroting what other people have said because you're a mean-spirited insecure SOB.

Run my filters, and see if the universe collapses or something.

A phase slope of zero is even better, and I don't have to compromise Q. I think a filter that can do this is cool, in its own right, despite it being, as you claim, non-causal.

It't really not worth answering your posts. You're not actually interested in electronics.