Hi chmf,

The way I see it, trimming is adjusting something inside a device or circuit so that the difference between the device output and a reference becomes (ideally) zero. Think of adjusting a resistor in a bandgap to get a certain output voltage. Trimming = changing something in the circuit.

Calibration, on the other hand, is to measure the difference between a device output and a reference, store it, and then compensate for it, e.g. storing the offset of an ADC in a microcontroller and subtracting it there... this leaves the circuit untouched.

CHMF,

   Not sure that there are any standard definitions. I would lean
more towards trimming as being a "hard" change to the system,
for example, laser trimming or blowing fuses. The traditional
analog types of circuit tuning. While calibration is a "soft" change
to the system, for example, digitally selecting a combination of
varactors that give the correct oscillation frequency for a VCO.
So the digital techniques used for digitally-assisted analog design
would count as calibration.

                                                         Best Regards,

                                                             Sheldon