The WRT Measure-Based Modeled de-embedding approach, as discussed in our
DesignCon2016 paper is very forgiving of lousy launch signal integrity (Tim
Wang Li simulated in ADS varying launch pathology and the impact for Beatty
standard estimation of DK. and LT), if they are all the same impedance profile
and are consistent. But like other de-embedding schemes it cannot deal with
unrepeatability, especially as you stated when you get past the 40Ghz realm.
This approach models the THRU and in situ DUT circuit, optimizing in both
time/frequency domain simultaneously then bifurcates a symmetric model. This
method only works if the EDA tool deals with both time and frequency domain
accurately, which ADS excels at.
We have not been overly impressed with the high density interconnect signal
integrity since the vendors (the Samtec Bullseye is an exception, but is only I
recall 20GHz connector) have not provided any clear reference design or real
data based on practical stack-ups - there are mechanical centric. Secondly,
the channel cost is really high (>$100/channel). We will revisit these higher
density interconnects based on future product offerings, especially from signal
integrity oriented companies.
BTW, really good paper at DesignCon2016.
- 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 9:21 AM, Bartlett, Josiah <josiah.bartlett@xxxxxxxxxxxxx>
wrote:
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 ;<http://tek.com/>
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <mailto:si-list-bounce@xxxxxxxxxxxxx>
[mailto: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 <mailto:erdinih@xxxxxxxxx>
Cc: hakim.sellaoui@xxxxxxxxxxxxxxx <mailto:hakim.sellaoui@xxxxxxxxxxxxxxx>;
si-list <si-list@xxxxxxxxxxxxx <mailto: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 donââ¬â¢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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