High efficiency solid-state light source and methods of use and manufacture

A lighting fixture, comprising:

• an array of solid-state light emitters including at least two modules, each module having a module array of multiple light emitters on a substrate, the substrates being electrically insulative and thermally conductive, the array mounted in the housing, wherein the solid-state light emitters are arranged on the substrates with a spacing determined by a required power density of a desired operation;
• a transistor-based current source within the housing electrically coupled to the array of solid-state light emitters, the current source receiving power from a power supply and balancing DC current between light-emitters in each module array and among the modules arrays;
• a heat sink attached to the housing arranged to dissipate heat from the array of solid-state light emitters;
• and
• drive circuitry within the housing to control operation of the solid-state light emitters.