IP3 of Flex 900 boards

GNU Radio
1

Hi Everyone:

Is there any information on the IP3 of Flex 900 boards. I was not lucky
to
find any specification documents on the boards.

I tried doing some experiments to find out the IP3 and my results show
37.5dBm, that is a good figure. I am not too sure whether it really is
so
high.

If anyone could please help me with any information that you may have
regarding the IP3 of Flex 900 boards, to that matter any other board
will
also give me a decent idea about these boards.

Thanks loads in advance.

Kind regards,

Shabbir

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2

sHabzbd wrote:

regarding the IP3 of Flex 900 boards, to that matter any other board will
also give me a decent idea about these boards.

The IP3 is a function of the gain setting you choose. But in any case,
your measurement of 37.5 dBm sounds very optimistic for any radio.

Matt

3

Thank you Matt. The IP3 measurement that I did was with 0 gain. I was
thinking that the value was very optimistic. Was hoping someone had a
value
for it.
Regards.

4

Well i have attached my experiment calculation for IP3.

Regards,

Shabbir

5

I am not sure whether the last email went through since the size of the
attachment was more than 100K.

Anyhow here is the attachment. Which shows my experiment results for
calculating IP3. I did make a mistake in interpreting my experiment
datas
earlier. The IP3 seems to be only 10dBm for the Flex 900 cards.

Regards,

Shabbir

6

The IP3 of the receiver. Sorry, I should have mentioned earlier.
Shabbir

7

OK, that makes sense. I was assuming you meant receiver IP3, but when
you labeled something as OIP3, it made me think you meant the TX.

Typically, for a device like an amplifier or mixer, the manufacturer
will quote it in either IIP3 or OIP3, depending on which sounds better
:slight_smile: Amplifiers have gain so the OIP3 is a bigger number, so they quote
that. Passive mixers have loss, so the IIP3 is a bigger number, and
they quote that.

Typically, for a complete receiver system, IIP3 is the number quoted,
and for a complete transmitter OIP3 is quoted, since those are the
measuring points.

In any case, +10 dBm for the IIP3 of the receivers is about in line with
reality, and is a very good number (if I do say so myself :slight_smile: for a
system like this. This will of course change with gain settings, in any
case.

Matt