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zero biased schottky detector problem - RF Cafe Forums
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Below are the old forum threads, including responses to the original posts.
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Post subject: zero biased schottky detector problem Posted:
Fri Aug 05, 2005 1:10 pm
I am sorry for the newbie question.
RF is not my expertise and I need a few concepts to set up a small test
I have designed a detector using zero biased schottky diode
in voltage doubler configuration using Agilents HSMS 2852 package. I
have mounted the SOT23 package along with relevant matching components
on a 31 mils FR-4 board. I provide RF input throught a signal generator
at 900 MHz using end launch SMA connectors. The output is measured using
a Volt meter.
My problem, is that the measured performance is
nowhere close to what is mentioned in the data sheet (which I also get
on simulation). The output DC voltage is much lower that mentioned in
data sheet at the input power levels. How can I go about "debugging"
Zero-bias Schottky detectorPosted: Sat Aug 06, 2005 11:12 am
Please tell us a bit more about the operating conditions - like what
is the RF voltage?
Voltage doubler circuits don't work too well
in the square-law region, so you have to have enough voltage to get
above it into the exponential region. In the case of Schottky diodes,
one reason simulations sometimes are inaccurate is poor modeling of
the diode capacitance.
Post subject: Posted: Sat Aug 06, 2005 7:06 pm
In the actual
system, the detector will be working with power levels of 0dBm to -25
However, right now, I am trying to test the performance of
the detector circuit alone. I am varying the input power level and trying
to reproduce the charecteristic shown in the data sheets and application
For instance, application note 1089, shows that the DC
output produced using the voltage doubler, at -30dBm, 900MHz input is
about 30mV. On measurement for my detector i get output of only about
I am just unsure about where the problem might lie and
to go about finding it.
subject: Voltage DoublerPosted: Sun Aug 07, 2005 7:44 pm
How does your circuit differ from the one in AN-1089, both schematically