Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

I don't know of a broad-spectrum site (i.e. one which is multivendor)
other than general datasheet-search sites such as datasheetarchive.com

One good place to start looking would be at www.avagotech.com - I
believe that Avago Technologies is the current inheritor of the line
of RF Schottky diodes originally made by HP and then by Agilent. Some
of these parts are useful up to quite a few GHz.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Feb 2, 11:34 pm, (Dave Platt) wrote:
Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

I don't know of a broad-spectrum site (i.e. one which is multivendor)
other than general datasheet-search sites such as datasheetarchive.com

One good place to start looking would be atwww.avagotech.com- I
believe that Avago Technologies is the current inheritor of the line
of RF Schottky diodes originally made by HP and then by Agilent. Some
of these parts are useful up to quite a few GHz.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Yes, that is correct about Avago. I believe I've come across diodes
there rated for use up to 40GHz, maybe 65GHz.

Also, look at other web sites (of companies with "new" names also!)
NXP used to be Philips. They definitely have some good RF detector
diodes. A Google search on "RF detector diode" just now turned up
several interesting hits, including some for sale on ebay. I saw
Vishay listed as an RF detector diode supplier, too, and I wasn't
aware they were really into that area--looks like they acquired
Telefunken, for another name change! But I suppose Suzy is looking
for non-surface-mount parts (from postings in another thread), and
that likely will be a problem for any new stuff. Pretty much
everything now has gone to tiny surface mount packages. -- OK, I
have to take that back. The Vishay web site has a kind of neat
feature and lets you look by package type--click on the picture of the
package. And it's real pictures, not line drawings. They DO have
glass axial lead RF diodes.

Cheers,
Tom

On 3 feb, 07:37, "Suzy" not@valid wrote:
Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

Hello Suzy,

The type of diode that will be best for your application depends on
the type of application.

For high level detectors (above several volts of RF input power), the
BAT62 is a good one up to some GHz. It has low capacitance (at Vj=0V)
and a reverse voltage of 40 V (fourty V). You cannot use it in low
noise mixers because of high intrinsic resistance.

Most of the HP or equivalent "hybrid" Shottky detector diodes (with
70V reverse rating) have far higher capacitance then the BAT62. Check
the datasheets, the 70V diodes are measured at Vj = -0.5V. At Vj=0V,
capacitance will be 1pF. For mixers, the best are the pure Shottky
rectifiers (that have a reverse voltage of less then 4..6V). For
Zero IF systems (Doppler radar, movement detection), other type of
shottky diodes are used (with low 1/f noise).

When you want to make a (calibrated) low level RF detector (for RF
levels 10mV), you need to consider the so-called "video
resistance" (that is the differential resistance of the diode at 0V
bias). To get full benefit of a low level detector, the DC voltmeter
(or buffer amplifier) must have a Rin video resistance. Otherwise
you cannot convert the DC voltage back to an RF input voltage.

The video resistance varies from about 10 kOhm (special "zero bias"
detector diodes) to several Mohm (for high barrier mixer diodes). Main
advantage of zero bias detector circuit is that you do not need to
build a temperature compensation (for compensating the about 2mV/degr.
C).

For UHF mixer or low level detection I use BAT15 (Cj 0.35pF at
Vj=0V).


Best regards,


Wim
PA3DJS
www.tetech.nl

Suzy wrote:
Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

A recollection from decades back are the 1N21, 1N23, 1N32, 1N53, 1N60, and
1N78 point-contact silicon diodes that were used as mixers well into the
microwave spectrum. Googling 1N23 produces 8000+ hits... including a
"Simple 2.4 GHz SWR Meter": (http://www.qsl.net/n9zia/24swr/index.html). I
see RF Parts (http://www.rfparts.com/) sells the 1N21 and 1N23.
MicroMetrics (http://www.micrometrics.com/) makes them, as well as various
schottky diodes suitable for sampling.
73,
Bryan WA7PRC

In article ,
AI4QJ wrote:

One good place to start looking would be at www.avagotech.com - I
believe that Avago Technologies is the current inheritor of the line
of RF Schottky diodes originally made by HP and then by Agilent. Some
of these parts are useful up to quite a few GHz.

I didn't see any UHF diodes on that site, did anybody else?

Click on "RFICs/Discretes" on the left. On the resulting page,
look in the "Product Tree" in the center, and click on "Schottky
Diodes".

The 5082-2800 series (glass-beaded) are specifically cited in their
data sheet as "particularly well suited for the UHF mixing needs of
the CATV marketplace".

In surface-mount, the HMPS-282x series are described as "RF/Microwave
mixer/detector diode", while the HSMS-282x "has been optimized for use
in RF applications, such as DC biased small signal detectors to 1.5
GHz, biased or unbiased large signal detectors to 4 GHz, mixers and
frequency multipliers to 6 GHz" according to the series data sheet.

I think that covers UHF pretty well, even if the web page and data
sheets don't use the specific term "UHF".

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

AI4QJ wrote:
"K7ITM" wrote in message
...

On Feb 2, 11:34 pm, (Dave Platt) wrote:

Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

I don't know of a broad-spectrum site (i.e. one which is multivendor)
other than general datasheet-search sites such as datasheetarchive.com

One good place to start looking would be atwww.avagotech.com- I
believe that Avago Technologies is the current inheritor of the line
of RF Schottky diodes originally made by HP and then by Agilent. Some
of these parts are useful up to quite a few GHz.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Yes, that is correct about Avago. I believe I've come across diodes
there rated for use up to 40GHz, maybe 65GHz.

Also, look at other web sites (of companies with "new" names also!)
NXP used to be Philips. They definitely have some good RF detector
diodes. A Google search on "RF detector diode" just now turned up
several interesting hits, including some for sale on ebay. I saw
Vishay listed as an RF detector diode supplier, too, and I wasn't
aware they were really into that area--looks like they acquired
Telefunken, for another name change! But I suppose Suzy is looking
for non-surface-mount parts (from postings in another thread), and
that likely will be a problem for any new stuff. Pretty much
everything now has gone to tiny surface mount packages. -- OK, I
have to take that back. The Vishay web site has a kind of neat
feature and lets you look by package type--click on the picture of the
package. And it's real pictures, not line drawings. They DO have
glass axial lead RF diodes.


But no website URL, as requested.


Google is your friend.

NXP (http://www.nxp.com/) is sold by Digikey (see, e.g., page 1152 of
the catalog). You might have better luck searching by the name Philips
to find part numbers.

http://www.avagotech.com/ for diodes from Avago (they have things like
the 1N5711) more to the point, lots of Ap notes.. see, for instance,
number 986 (Avago was part of HP, but actually was originally
Avantek... on the other hand, HP always made diodes, so maybe Avago is
some of Avantek (MMIC) and some of HP (diodes))

http://www.vishay.com/ for Vishay. Look for small signal diodes


One should also look at Microwaves 101
http://www.microwaves101.com/encyclopedia/detectors.cfm

and they have a "where are they now" page on their website, to help
track down who sells brand X now.
http://www.microwaves101.com/encyclopedia/wherenow.cfm

AI4QJ wrote:
"Bryan" wrote in message
...

Suzy wrote:

Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

A recollection from decades back are the 1N21, 1N23, 1N32, 1N53, 1N60, and
1N78 point-contact silicon diodes that were used as mixers well into the
microwave spectrum. Googling 1N23 produces 8000+ hits... including a
"Simple 2.4 GHz SWR Meter": (http://www.qsl.net/n9zia/24swr/index.html). I
see RF Parts (http://www.rfparts.com/) sells the 1N21 and 1N23.
MicroMetrics (http://www.micrometrics.com/) makes them, as well as various
schottky diodes suitable for sampling.
73,
Bryan WA7PRC


Interesting but this is not what was requested.




I don't think you'll find a website that compares diodes for RF
performance.

A couple reasons spring to mind:
1) Most RF designers have their favorite parts that they've used before,
so they will tend to just use them again. If their favorite part
doesn't work, then they'll start hunting through the pile of datasheets
and books or ask around for suggestions (e.g. just like on this list)

2) The performance is highly application specific. You can look at the
basic numbers (PIV, forward resistance, capacitance, etc.) to get an
idea, but it's really going to come down to how it works in YOUR
circuit, and that's usually a breadboarding or modeling exercise (most
parts have pretty good SPICE or other models available). Just because
manufacturer X's 1n5711 works great in my mixer doesn't mean it will
work great in your frequency tripler or someone else's RF switch.

3) There are significant differences in performance between
manufacturers for the same JEDEC partnumber (e.g. 1n5711). In a lot of
high performance applications, you actually depend on some non-datasheet
performance property. For instance, there's a small company in England
that makes a low noise JFET that is unique in the world and prized by
folks building charge/voltage converters, even though it's got a
standard 2N number. And then, they still get a batch of them and hand
select.

4) Parts selection is something of competitive value. Someone who
designs RF stuff for a living (i.e. someone who would be likely to know
all the trade offs between various part types and mfrs and could
generate a comparative website) is going to be encouraged by their
employer to not publish this for the whole wide world.

On Feb 5, 9:29 am, Jim Lux wrote:
AI4QJ wrote:
"Bryan" wrote in message
m...

Suzy wrote:

Looking for a website that gives comparative performance of diodes (max
frequency for UHF use)

A recollection from decades back are the 1N21, 1N23, 1N32, 1N53, 1N60, and
1N78 point-contact silicon diodes that were used as mixers well into the
microwave spectrum. Googling 1N23 produces 8000+ hits... including a
"Simple 2.4 GHz SWR Meter": (http://www.qsl.net/n9zia/24swr/index.html). I
see RF Parts (http://www.rfparts.com/) sells the 1N21 and 1N23.
MicroMetrics (http://www.micrometrics.com/) makes them, as well as various
schottky diodes suitable for sampling.
73,
Bryan WA7PRC

Interesting but this is not what was requested.

I don't think you'll find a website that compares diodes for RF
performance.

A couple reasons spring to mind:
1) Most RF designers have their favorite parts that they've used before,
so they will tend to just use them again. If their favorite part
doesn't work, then they'll start hunting through the pile of datasheets
and books or ask around for suggestions (e.g. just like on this list)

2) The performance is highly application specific. You can look at the
basic numbers (PIV, forward resistance, capacitance, etc.) to get an
idea, but it's really going to come down to how it works in YOUR
circuit, and that's usually a breadboarding or modeling exercise (most
parts have pretty good SPICE or other models available). Just because
manufacturer X's 1n5711 works great in my mixer doesn't mean it will
work great in your frequency tripler or someone else's RF switch.

3) There are significant differences in performance between
manufacturers for the same JEDEC partnumber (e.g. 1n5711). In a lot of
high performance applications, you actually depend on some non-datasheet
performance property. For instance, there's a small company in England
that makes a low noise JFET that is unique in the world and prized by
folks building charge/voltage converters, even though it's got a
standard 2N number. And then, they still get a batch of them and hand
select.

4) Parts selection is something of competitive value. Someone who
designs RF stuff for a living (i.e. someone who would be likely to know
all the trade offs between various part types and mfrs and could
generate a comparative website) is going to be encouraged by their
employer to not publish this for the whole wide world.



And of course there's the other side of the coin on number 4: a
manufacturer isn't going to provide a comparison with other
manufacturers' parts for at least a couple reasons. They want to
focus attention on their own parts, and they have no control over any
changes another manufacturer may make in their parts and thus no way
to insure accuracy of such a comparison.

The tough part of Suzy's quest is finding an acceptable diode in non-
surface-mount, it seems to me. I did find that a common 1N4148 non-
Schottky performed in my test detector circuit at 450MHz better than I
expected, and better than some other diodes I tried like 1N34 and
several other germaniums, and an axial-leaded Schottky or two in the
high voltage, high capacitance signal diode class that I believe Wim
warned against.

I really appreciated Wim's posting on this topic, and also yours,
Jim. Thanks.

Cheers,
Tom

K7ITM wrote in
:

....
The tough part of Suzy's quest is finding an acceptable diode in non-
surface-mount, it seems to me. I did find that a common 1N4148 non-
Schottky performed in my test detector circuit at 450MHz better than I
expected, and better than some other diodes I tried like 1N34 and
several other germaniums, and an axial-leaded Schottky or two in the
high voltage, high capacitance signal diode class that I believe Wim
warned against.
Presuming this is for the 70cm reflectometer, I have already pointed
Suzy to two Australian retailers with diodes that should work.

My assumption is that she will design the detector to work above the
square law region, and the usual practice is then to design the coupler
so that the dc voltage is much greater than the diode voltage drop, and
the scale shape is relatively independent of the diode drop.

Another retailer is minikits.com.au. Mark has 1N5711 for 0.66, and it
will probably cost $7 for postage. Last time I tried to buy diodes from
Mark, he wanted to know what I wanted them for, whether it was a worthy
project, and would deem to sell me only a small quantity. I subsequenctly
bought a couple of hundred 1N5711 on Ebay for $15.

Ebay is a huge source of schottky diodes (if you must prefer schottky).
Just search for schottky, sbd, barrier, hot carrier etc, then get the
specs for each one and see if they are suitable. Thing is that most the
signal ones will be SM packages of one or two diodes, but they can be
used with pigtails attached.

There are 9 listings on Ebay right now for 1N5711.

Owen