IV. CONFIGURABLE CURRENT MIRROR
In series-parallel configuration, there are multiple strings of series LEOs. It is always better to limit the number of LEOs
in series to minimize total VI (threshold voltage) mismatch between strings. Due to manufacturing tolerances and material
properties, fit can vary between LEDs even if they are from the same wafer. Depending on the technology used, the range in difference can be a few millivolts to upto a volt. When multiple LEOs are connected in series, this VI mismatch
between LEOs adds up and becomes significant. In seriesparallel configuration, if the string voltage is significantly
different between stings, the current through each string will vary (become imbalanced) when a single constant current
source is used.