Using TMP36 with AD8362 at 1 MHz

I have a design that is using the TMP36 to compensate for temperature changes of the AD8362 Log Amp. The input to the AD8362 is 1 MHz. The chart in the application note only goes down to 900 MHz when selecting the resisters shown in the application. How do I calculate the resistors for 1 MHz operation of this log amp?

  • You need to first figure out the native drift of the devices at 1 MHz by applying a fixed input power and cycling the device over temperature. You can go from -40 to +85 or a subset of this temperature range. Ultimately, you need to figure out the drift in mV/degC. Once you have that number, you can use the equations in AN-653 to figure out what resistor values to use.

    I should note that there are now newer and better parts than AD8362 with better temperature drift. Take a look at HMC1120 for example. You will get as good if not better temperature drift from this device without any external temperature compensation.