Hi Alexander,
As I mentioned before, IQ phase error is quite stable over
temperature in 900/1800MHz region so let us put it aside. This can
be tuned and fixed in production.
On the other hand, DC offset and LO leakage are temperature
dependent as one would expect. However, they can be calibrated in
the product as well not just in the lab. You need just to trigger
built in DC cal blocks and optionally use RF loop back to further
improve LO leakage. If you want to avoid temperature sensor you
have an option to do these calibrations regularly, every 30min-1h
for example. This should track the temperature change without
having the sensor on board.
Our other customers are using both approaches, with and without
temperature sensor, depending on application and spec. If they
have on board temperature sensor they are using it for multiple
purpose such as monitoring BB, PA, etc.
Best regards, Srdjan
On 26/07/2012 16:48, Alexander Chemeris wrote:
On Thu, Jul 26, 2012 at 4:37 PM, Alexander Chemeris
<alexander.chemeris@gmail.com> wrote:
On Thu, Jul 26, 2012 at 3:31 PM, Srdjan Milenkovic
<s.milenkovic@limemicro.com> wrote:
Combining Thomas's idea of DC recalibration and, if necessary, making
look
up table for IQ phase error correction vs temperature should put us in
good
position to meet the specs.
Well, AFAIK, LMS6002D doesn't have a temperature sensor built in and
this means we have to install an external one, which again increase
BoM cost. Is that's how this issue is solved by your other customers?
I wonder is there a way to solve this without introducing a
temperature compensation loop.
Let me clarify - DC offset re-calibration is (more or less) fine in
lab setup, but it's expensive to manufacture if we have to add
temperature sensors and put every unit into a temperature camera for
calibration.
--
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru