Cal kits can still be a problem, but there are a few newly interoduced threaded
or otherwise stabilized mini connectors (Smaller than SMA) that offer high
density but more repeatable connection than snap-in, such as 0.9mm SuperMini
(SW Microwave), and SMPM-T (Huber+Suhner/open standard), or some of the high
density Multi-port mini coax press-on to cable test connectors (Huber+Suhner,
Rosenberger, Ardent, etc).
The best way to approach the connector situation is to evaluate the measurement
requirements (bandwidth, phase stability, time resolution, etc.) and make the
connector choice from there. Using an SMPM at, say, 10 Ghz is much different
than using it at 40 Ghz. Phase stability/repeatability typically makes the most
difference in cal-through or deembed-thru accuracy for connectors, especially
when using TRL or other schemes that try to move the reference plane past the
connector.
Josiah Bartlett
Principal Engineer
Tektronix, Inc.
T 503.627.2946
http://tek.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Alfred P. Neves
Sent: Wednesday, October 12, 2016 7:48 AM
To: erdinih@xxxxxxxxx
Cc: hakim.sellaoui@xxxxxxxxxxxxxxx; si-list <si-list@xxxxxxxxxxxxx>
Subject: [SI-LIST] Re: Input Matching for SMA Connectors
Our data and analysis suggest mini connectors suffer from connector
repeatability, and secondly I don’t recall cal kits being available for them
which complicates location of the reference plane. As you point out, the
increased density for practical test fixtures is a good one. The WRT Channel
Modeling platforms have a 1inch center - center spacing requirement for 2.92m
through 1.85mm connectors to accommodate the heavier VNA cables, which does
hobble density a bit.
The Keysight folks did write a paper in last DesignCon to use their
de-embedding method to de-embed them, effectively moving the reference plane.
- Al
Products for the Signal Integrity Practitioner
Alfred P. Neves
Chief Technologist
Office: 503-679-2429
www.wildrivertech.com <http://www.wildrivertech.com/>
2015 Best In Design&Test Finalist
On Oct 12, 2016, at 7:32 AM, Ihsan Erdin <erdinih@xxxxxxxxx> wrote:
Hakim,
Forget SMA; they're too bulky for most PCB applications discussed
here. In the past, I had a similar concern and used mini-SMP from
Rosenberger (but there are other sources, too) Those tiny connectors
are good for up to 65GHz and won't take up much space on a PCB. Still,
you'll need to flare up diff. traces where they need to be routed to the
connectors.
Since your VNA probe connectors are usually of SMA type you'll also
need at least a pair of SMA-miniSMP adapters which are quite expensive.
Regards.
Ihsan Erdin
On Tue, Oct 11, 2016 at 7:25 AM, Hakim Sellaoui <
hakim.sellaoui@xxxxxxxxxxxxxxx> wrote:
Hi all,
I'm designing a test board that will have differential trace widths
of 4 mil and I want to connect SMA connectors to them, but I'm not
sure what connector would be suitable as the ones I've found have
connector widths that are neither equal to or smaller than the trace
widths, as well as the recommended pad sizes are much larger. For an
RF design I did at Uni, I just added a quarter wave transformer to
provide the matching at the operating frequency; is it still possible
to do this with a high-speed design with a 200 ps rise time (5 GHz) signal?
Or can anyone recommended a way to connect VNA coaxial cables to a
PCB with trace widths around 4 mils, such that the Zo is maintained.
Thanks,
--
Hakim Sellaoui
Associate Hardware Engineer
DisplayLink (UK) Limited
Tel: +44 (0)1223 443920
Fax: +44 (0)1223 443921
E:
hakim.sellaoui@xxxxxxxxxxxxxxx<mailto:hakim.sellaoui@xxxxxxxxxxxxxxx>
W: http://www.displaylink.com/
140 Science Park, Milton Road,
Cambridge, CB4 0GF,
United Kingdom.
Registered in England No. 04811048
DisplayLink Corp.
A US incorporated company.
480 S. California Avenue Ste 305, Palo Alto, CA 94306, USA.
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