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of RF Schottky diodes originally made by HP and then by Agilent.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of RF Schottky diodes originally made by HP and then by Agilent.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