Filter Design Software

Pull down Zverev. ;)

Cheers

Phil Hobbs

-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203 Briarcliff Manor NY 10510

hobbs at electrooptical dot net

On 1/27/2015 11:33 AM, Jim Thompson wrote: > I need a filter with the following specs: > > Center frequency: 2MHz > Nose Bandwidth (-3dB): 20kHz > -60dB Bandwidth: 40kHz > > Cauer/Elliptic type would be fine > > Need: Pole locations, A+jB, Zero locations. > > The free software out there won't do more than third order. > > ...Jim Thompson >

-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203 Briarcliff Manor NY 10510

hobbs at electrooptical dot net

...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

[snip]

My copy is still in a moving box somewhere :-( ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

For 0.05dB ripple elliptic

-6202 +/- 2.003M

-6182 +/- 1.997M

-3615 +/- 2.008M

-3584 +/- 1.992M

-1090 +/- 2.011M

-1078 +/- 1.989M

zeros

+/- 2.024M +/- 2.018M +/- 1.982M +/- 1.976M 0

Some kinda nasty high-Q poles there.

Cheers

Phil Hobbs

20kHz / 2MHz -- of course there are. That's in crystal filter territory.

--
www.wescottdesign.com

Naaaah! Just multiple poles and zeroes. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Qs of several hundred at 2 MHz are a bit awkward, I expect--too low for crystals, too high for ordinary LCs, at a frequency too low for coaxials.

Cheers

Phil Hobbs

Pan (or Giganews) keeps not posting my replies -- here it is again with the "reply-to" list trimmed:

That's asking for some awfully high Q resonators (certainly Q > 100). I think you're outside of what you can do with coils, and into crystal filter territory.

A custom crystal filter is going to be big, heavy, and expensive in engineering time, parts, and alignment time. That's assuming you can find someone who'll make it for you, because these days if you have a task like that it's done with DSP.

You may be able to find an off-the-shelf filter that has the bandwidth and shape factor you need but not at 2MHz carrier frequency, in which case you can build a superheterodyne radio and either take your output at the radio's IF, or have the thing regenerate signal back at 2MHz.

DSP, using today's components, will be smaller, lighter, quicker and cheaper -- the only thing it won't be is less power hungry, and depending on what you need around your filter, the cost of using DSP may not be all that great.

--
www.wescottdesign.com

Crystal filters can be implemented to do this, but I think you need to use some fancy techniques. "Mesh" filters that use transformer-coupled pairs of crystals will get around a crystal's parallel resonance, and I've seen 20kHz bandwidth filters -- but those were at 9MHz center frequency. I have heard of filters that use LC filters to establish the general shape, then use crystals to establish steep skirts, but that's a high-falutin' military radio technique from the 1960's -- today, you can built an entire high-performance radio that uses DSP into the space of a crystal filter, and you may not use more power for it than you'd need in the amp to overcome the filter's insertion loss.

--
www.wescottdesign.com

Have fun, then. Particularly when the furnace or air conditioning kicks on and the alignment goes totally out of whack.

--
www.wescottdesign.com

Am 28.01.2015 um 00:44 schrieb Phil Hobbs:

I have some pot cores, Siemens K1 material, wound with RF Litz wire that have a Q of 300-400 on 7 MHz. They are > 30 years old, from old telephone switching systems. Maybe EPCOS still makes these pot cores. Red and maybe yellow Amidon toroids can be nearly as good.

regards, Gerhard

(they make a pretty good preselector for ham radio!)

Pot cores can be had with TCs that compensate certain caps, and with adjustable slug tuners... probably both needed here.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Going to do it with an active filter ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

FDNR?

--


----Android NewsGroup Reader---- 
http://usenet.sinaapp.com/

You'll need trimpots or mdacs or dpots or laser trimming or something to tune it. TCs will be interesting too.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Possibly. Definitely gyrator-based because that architecture is very stable. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Crikey, it's only audio... 2MHz... not like it was 200MHz. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Look at those pole and zero locations. Fractions of a per cent apart. You'll need some outrageous opamp GBWs, too, to get high Q sections around 2 MHz.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com