Building a Temperature Compensated Voltage Reference

Why climb Everest…? Because it is there.

?Here is my latest weekend project. This has been rattling around in my head for a couple of years so I thought I would finally channel my inner Bob Widlar and build it.

It is a temperature compensated voltage reference, based on the MAX6325. Glued to the top of the reference is an ADT7422 precision temperature sensor that measures the temperature of the MAX6325 to a precision of 0.1C and feeds this into a MAX32625PICO microprocessor. The micro is connected to an E2 memory that stores the drift parameters of the voltage reference. The micro uses these drift parameters to drive a 16 bit DAC (MAX541) that calibrates out the drift of the voltage reference using a chopper stabilised amplifier, thus creating a thermally stable voltage reference.

When Mrs Bramble is not looking, I will put it in the oven and measure its drift. I have also been in contact with a local calibration company who have expressed an interest in its design and want to calibrate it for me, for a small sum. It helped when I told them my company makes the voltage reference (LTZ1000) inside the piece of test equipment they are going to use to calibrate it (HP3458A)

Why build it…? Just to see if I can…