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Alexander Chemeris alexander.chemeris at gmail.comHi Srdjan, Thank you for the comment. Unfortunately, we can't perform regular re-calibration, because a GSM base station can't stop transmitting. This means we need a full blow temperature sensor and this is a bad news, as we have to create UmTRXv3 to add it. This is something you should definitely consider for your next-gen chip - an embedded temperature sensor. Do you know how sensitive those parameters are to a temperature? I.e. should we calibrate adjust them every centigrade or every five centigrade? On Fri, Jul 27, 2012 at 6:28 PM, Srdjan Milenkovic <s.milenkovic at limemicro.com> wrote: > 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 at gmail.com> wrote: > > On Thu, Jul 26, 2012 at 3:31 PM, Srdjan Milenkovic > <s.milenkovic at 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 > > -- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru