Last year I developed a voltage reference using an HV LED. Unfortunately these devices from OSRAM seem to be discontinued. I managed to buy enough parts for my own use though. What is interesting from these LEDs is that the dynamic resistance is low. About 150Ω with good current, or between 300Ω to 500Ω. Tempco is very low and with such a low dynamic resistance, they are great for creating a voltage reference with a stable CCS:
The LEDs are extremely bright and found that with a 1mA current are dim enough whilst retaining the stability needed. I have a cap multiplier arrangement and the LED array is fed by a stable CCS. Jumpers on the board allow bypassing LEDs and there is also the option to use a trimmer for variable voltage adjustment. Very handy for screen grid supply and phono stages. The reference voltage is extremely quiet with more than 100dB PSR.
