I need a temperature compensated log amp to convert a logarithmic varying resistance to more or less linear voltage. The temperature compenstation can be done in software if I can know the exact compensation formula with temperature as I already have a temperature sensor on board.
i think you can do it in another way. First you must know what type of temp sensor you have, e.g. pt100, type of thermocouple (J K S or so on).
Then look at Maxim and Linear Technologie or other manufactors for special chips for themperature measurement. There are some chips on the market with this feature.
For example: you have an themocouple type K, so you choose the right chip for this and you have a linear voltage output.
I think you did not get my point. Temperature is not a problem. I already have a sensor (thermistor based) and have the temperature value calculated in software. Now I want this value to be applied to a logarithmic amplifier to correct its response for temperature. Since most log amps are based on the log response of Vbe of a transistor and this Vbe is highly temperature dependent. I dont know exactly how to correct the output voltage for temperature. A simple log amp circuit using simple op-amp can be found in any op-amp book or in the n@tion@l semi website. But its temperature dependence is not documented in detail.