×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

CPW SM attenuator chip

CPW SM attenuator chip

CPW SM attenuator chip

(OP)
I am using a nice little 3dB surface mount attenuator, roughly 0805 size, which works up to 20GHz. Unfortunately it only has three terminals; in, out, and ground. What I really want is the same thing but with two ground terminals so it fits more symmetrically on coplanar waveguide.

Has anyone seen such a device? Manufacturer’s name?

RE: CPW SM attenuator chip

(OP)
Thanks for the link.

It is interesting that all three of the mini-circuits offerings have two ground connections. It is hard to imagine being able to design such a component to have only one ground in fact!

Pity they only work to just above DC

RE: CPW SM attenuator chip

Why not make your own attenuator using R Card (Resistive Card).
It's perfect for CPW, it's a few mils thick and just lay it across your contacts similar to a chip resistor used in an isolated power divider. Trim the length to get the 3 dB loss. RCard comes in impedance 10-400 ohm's per square. This would be similar to a rotary vain attenuator in waveguide too, just some lossy stuff in your field.

Now the bad part, the perfect 3 dB loss won't be seen over a wide bandwidth. It's like the loss of a cable, more loss at fhigh. So depending on your bandwidth, it may be usable.

kch

RE: CPW SM attenuator chip

(OP)
It's a broadband application, say 1GHz to 20GHz, and non flat response is unacceptable. However I have not heard of this stuff before so the idea is interesting anyway. Thanks.

RE: CPW SM attenuator chip

I believe that a normal attenuator has a T or Pi shaped arrangement of resistors. If you have chip resistors available with the proper impedances, can't you add them into your CPW lines and between the lines to get what you want. Probably won't work at 20 ghz unless the parts are very tiny and you can get them very close together.

Good luck.

kch

RE: CPW SM attenuator chip

(OP)
Well that is of course the other option I was looking at. It is difficult (= impossible) to quantify the VSWR of such a "homemade" attenuator, but if I make them into an "H" (5 resistors) or a "+" (4 resistors) it will certainly have the desired physical symmetry.

RE: CPW SM attenuator chip

You can buy dielectrics with Rcard underneath the copper cladding. We are doing that now for antenna development. I think the company is Omegafoil I believe, a coworker is designing it. With that you may be able to use etching to make your circuit. I saw that www.E-fab.com uses it
Previously, I worked on stripline Microwave Lenses using this material where we etched this Omegafoil over 4-18 ghz bandwidths to make a 2:1 power divider resistive load for isolation purposes. The layers are dielectric/Rcard/copper cladding. Removing the copper cladding leaves Rcard which is in contact with the copper foil.
If you etched your 4 or 5 resistors, that might work.


kch.

RE: CPW SM attenuator chip

You might want to look at Micrometrics.

I have designed both T and Pi attenuator chips that they have manufactured for me for use to 18 Ghz, but they are larger than 0805 in order to handle higher power levels.

These chips  http://www.micrometrics.com/pdfs/AP_Datasheet.pdf
are very small (.03" x .03") and have 4 leads (Pi configuration) and are rated to 40 GHz.

David

RE: CPW SM attenuator chip

(OP)
Nice one. Thanks.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close