Analog integrated circuits design for driving the light-emitting diode (LED) based projection display systems
Day, Jacob W
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This dissertation mainly presents the design, simulation and testing of three novel analog integrated circuits (IC) systems for driving the light-emitting diode (LED) based projection displays. The first is a complementary metal-oxide semiconductor (CMOS) IC that is used in conjunction with a micro-emitter array to create a self-emissive micro display. This novel approach utilizes a mature 0.6µm CMOS IC process and parallel data processing to achieve 60Hz refresh rate for a 640 x 480 pixel (VGA) display. The second is a high current LED driver with novel dual current regulation for high efficiency steady state operation as well as with well-controlled transient switching behaviors. The third one is a periphery circuit that combines a low drop-out (LDO) voltage regulator and digital oscillator that provides an accurate clocking signal for switching DC-DC converters as well as the digital circuitry used to regulate the current in high power LED applications. These have all been implemented in silicon integrated circuits (ICs) and tested to verify expected functionality. The micro-emitter array is capable of displaying a monochrome gray scale image as programmed via a National Instruments (NI) data acquisition (DAQ) card. The brightness level is such that, when shone through an optic lens, the projected image can be seen clearly on a viewing surface with the room fully lit. The LED driver designed and reported here regulates transient current to within 10% of the desired steady state current. A novel two-loop regulation techniques works seamlessly together with no need for user-controlled switching between modes. The LDO and digital oscillator are in full production in a number of commercially available ICs offered by Texas Instruments (TI). The voltage regulator has proven to maintain a reliable voltage across millions of units. The oscillator also provides a quality clock for DC-DC converters that receive high levels of customer satisfactions.