Tapering Transmisson Line in EAGLE CAD

Am 11.07.2012 15:40, schrieb Usman Ali:

I have designed something shown in the attached image(zoomed only to show

ic connections).

Since all the lines are 50 ohm, their width is about 0.45 mm. a close look

shows that the IC pads are smaller then the microstrip line i.e 0.25 mm.

I advise NOT to connect wires of that large width to the IC.

Will this huge width affect the neighboring pad which are connected to

ground plan.

Yes. The possibility of short-circuits during manufacturing will be MUCH

higher, and you might even need to pay extra due to very small copper

distances.

From the data sheet they suggests the line tip attaching the IC PAD shall

be tappered.

 

So how can i apply tapering in EAGLE CAD, and what is the theory behing it,

how to select tapering width and how much length to tapered..

There is NO special function for that, so just draw it manually:

  1. Using the SMD width of your IC, route from the IC to where the wire

     should get thicker.

  2. Change the width of future wires to the large width that you need.

  3. Route from the last point to wherever you want to.

  4. Now you have a thin wire getting thicker at the desired point.

  5. If you want the wire thickness to NOT change abruptly, choose the

     thin width again and insert additional sloping wires. Pay attention

     that the new wire starts EXACTLY on one existing wire, otherwise

     the DRC will complain later.

Andreas Weidner

Am 11.07.2012 15:40, schrieb Usman Ali:

I have designed something shown in the attached image(zoomed only to show

ic connections).

Since all the lines are 50 ohm, their width is about 0.45 mm. a close look

shows that the IC pads are smaller then the microstrip line i.e 0.25 mm.

I advise NOT to connect wires of that large width to the IC.

Will this huge width affect the neighboring pad which are connected to

ground plan.

Yes. The possibility of short-circuits during manufacturing will be MUCH

higher, and you might even need to pay extra due to very small copper

distances.

From the data sheet they suggests the line tip attaching the IC PAD shall

be tappered.

 

So how can i apply tapering in EAGLE CAD, and what is the theory behing it,

how to select tapering width and how much length to tapered..

There is NO special function for that, so just draw it manually:

  1. Using the SMD width of your IC, route from the IC to where the wire

     should get thicker.

  2. Change the width of future wires to the large width that you need.

  3. Route from the last point to wherever you want to.

  4. Now you have a thin wire getting thicker at the desired point.

  5. If you want the wire thickness to NOT change abruptly, choose the

     thin width again and insert additional sloping wires. Pay attention

     that the new wire starts EXACTLY on one existing wire, otherwise

     the DRC will complain later.

Andreas Weidner