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 bed.
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" this problem?
Post subject: Zero-bias Schottky
detectorPosted: Sat Aug 06, 2005 11:12 am
us a bit more about the operating conditions - like what is the
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
In the actual system, the detector will be working with power
levels of 0dBm to -25 dBm.
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 notes.
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 1 -2mV.
just unsure about where the problem might lie and to go about finding
Post subject: Voltage
DoublerPosted: Sun Aug 07, 2005 7:44 pm
How does your
circuit differ from the one in AN-1089, both schematically and physically?