Using smaller CMOS nodes for the design of backplanes for light modulator enables the integration of additional features. This paper reports on a backplane designed in 28nm technology which embeds a complete framebuffer as well as a programmable high speed data interface which can realize up to 576Gbit/s data transfer rate to pixel array utilizing a 1440 x 1080 resolution with a 2.5 micron pixel capable for LCOS, OLED and micro-LED front planes. The programmable modulation scheme will be discussed in detail using typical scanning examples.
It is commonly known for digital logic integrated circuitries that they heavily scale with down-scaling of the process node enabling the integration of more functionality. However, this was not true so far for OLED microdisplays which were basically stuck at 90nm…250nm process nodes for several reasons. This paper will present a new approach to realize a microdisplay architecture with extended functionality as well as a first implementation in 28nm utilizing very small pixels of 2.5um, a flexible interface architecture, framerates up to 10kHz along with integration of totally new driving schemes to serve the power and form factor requirements of upcoming near-to-eye systems in AR/VR/MR applications.
Emissive OLED-on-silicon microdisplays have been considered being opaque only so far. However, modern and advanced silicon CMOS process nodes are increasingly made on silicon-on-insulator (SOI) substrates. By separating the SOI handle wafer from the buried oxide (BOX) layer (that has the active silicon on top) and applying space-cautious layout design of the CMOS active devices as well as wiring layers it is possible to achieve semitransparent, high-resolution CMOS backplanes for microdisplays. Similar to regular OLED-on-silicon the emissive frontplane becomes embedded by waferlevel OLED post-processing. Yet, depending on pixel density and array layout a microdisplay transparency of <20% can be achieved now. Consequently, the semi-transparent microdisplay becomes the optical combiner itself, eliminating the exit pupil expander (EPE), which drastically improves the optical efficiency from the light source into the eye box. Additionally, new high-brightness OLED achieving <35kcd/m² in monochrome, or 10kcd/m² in color versions, and their integration onto the OLED-on-SOI platform and an ultra-low power pixel cell backplane architecture (power consumption <10mW) pave the way for matching both form factor and battery life requirements in optical see-through NTE, enabling new optical concepts for augmented-reality (AR) devices.
OLED-on-Silicon technology has reached industry maturity for OLED (organic light emitting diode) microdisplays, e.g., in near-to-eye applications. Anyway, there is a huge amount of further applications, which can be addressed with an organic frontplane on an integrated CMOS backplane, e.g., OPD (organic photo diode). This paper will report on latest results in the field of OPD-on-silicon sensing as well as OLED-on-silicon displays, sketching up the impact of a universal photonic platform comprising emitters, photodetectors and CMOS driving and read-out circuitry, based on application scenarios.
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