Butterworth bandpass filter question
I am trying to scale an existing front end receiver (butterworth
bandpass) filter to a different frequency range. Unfortunately, it has a transformer in the original design, so I'm stuck. I also don't know how to handle the load presented by the active front end component other than it's probably not significantly reactive. The existing filter is for a 7 Mhz receiver, I'd like to have a similar filter design for 50 to 200 Khz. The filter components and transformer winding details are in the document at: http://www.amqrp.org/kits/softrock40...0Assy%20v1.pdf The input chip is an FST3126, spec sheet is at: http://www.fairchildsemi.com/ds/FS/FST3126.pdf The spec for the T30-2 transformer core is at: http://partsandkits.com/T30-2.htm I have aade filter design software, but it isn't allowing me to plug in the transformer into the design page of the software....so, I need to know it's equivalent circuit I think. The transformer winding details are on page 4 of the document and the schematic of the front end is page 9. Ultimately, I need new values for L1, L2, C20, C21 and C22. If someone can give me a reasonable guess as to the equivalent circuit of the transformer and the IC (U5), I can do the rest of the job myself using the aade filter software. Thanks, T |
On Sun, 11 Sep 2005 12:14:11 -0400, TRABEM wrote:
Get the free software program call RFsim99 lets you design buttrworth filters. |
I am trying to scale an existing front end receiver (butterworth
bandpass) filter to a different frequency range. ===================================== How do you know it is a Butterworth as distinct from other types? |
A butterworth is a butterworth............in any discussion of the
butterworth filter, you will see this schematic. Asking how I know it's a butterworth is a little like asking how I know a car is a car. However, I don't know it all.........perhaps it's closely related to a butterworth, but called something else??? Let me know if I've made an error please. T On Mon, 12 Sep 2005 06:07:31 +0000 (UTC), "Reg Edwards" wrote: I am trying to scale an existing front end receiver (butterworth bandpass) filter to a different frequency range. ===================================== How do you know it is a Butterworth as distinct from other types? |
TRABEM schrieb im Newsbeitrag
... A butterworth is a butterworth............in any discussion of the butterworth filter, you will see this schematic. Asking how I know it's a butterworth is a little like asking how I know a car is a car. However, I don't know it all.........perhaps it's closely related to a butterworth, but called something else??? Let me know if I've made an error please. T Hello T, a Bessel filter would have the same structure. The value of the components define what filter type it is. Bessel: max. flat group delay Butterworth: max flat frequency response You can also make a filter with this structure which is anything between both types. Best regards, Helmut |
a Bessel filter would have the same structure. The value of the components define what filter type it is. Bessel: max. flat group delay Butterworth: max flat frequency response Cool, didn't know that. At VLF, the inductances are becoming quite large, requiring a toroid core for even a simple inductor. What are the advantages/disadvantages of each type relative to inductor size requirements? Maybe I should be looking at a bessel instead of a butterworth....... GL to all. T |
On Mon, 12 Sep 2005 12:18:52 -0400, TRABEM wrote:
A butterworth is a butterworth............in any discussion of the butterworth filter, you will see this schematic. Asking how I know it's a butterworth is a little like asking how I know a car is a car. However, I don't know it all.........perhaps it's closely related to a butterworth, but called something else??? Let me know if I've made an error please. T On Mon, 12 Sep 2005 06:07:31 +0000 (UTC), "Reg Edwards" wrote: I am trying to scale an existing front end receiver (butterworth bandpass) filter to a different frequency range. ===================================== How do you know it is a Butterworth as distinct from other types? A Butterworth filter is a Chebyshev filter with No ripple in the passband. |
"TRABEM" bravely wrote to "All" (12 Sep 05 12:18:52)
--- on the heady topic of " Butterworth bandpass filter question" I thought it was a turkey until I opened a filter cookbook... Isn't it flat smooth response without overshoot as opposed to Tchebychev with a little overshoot but faster risetime? Bessel is something in between these? Where do they find these names!!! M*i*k*e TR From: TRABEM TR Subject: Butterworth bandpass filter question TR Xref: core-easynews sci.electronics.components:101732 TR sci.electronics.design:505281 sci.electronics.repair:341949 TR A butterworth is a butterworth............in any discussion of the TR butterworth filter, you will see this schematic. TR Asking how I know it's a butterworth is a little like asking how I TR know a car is a car. TR However, I don't know it all.........perhaps it's closely related to a TR butterworth, but called something else??? TR Let me know if I've made an error please. TR T TR On Mon, 12 Sep 2005 06:07:31 +0000 (UTC), "Reg Edwards" TR wrote: I am trying to scale an existing front end receiver (butterworth bandpass) filter to a different frequency range. =3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d= 3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d =3d=3d=3d=3d How do you know it is a Butterworth as distinct from other types? .... If all else fails, hurl it across the room a few times! |
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