4 research outputs found
LED receiver impedance and its effects on LED-LED visible light communications
This paper experimentally demonstrates that the AC impedance spectrum of the
LED as a photodetector heavily depends on the received optical power, which may
cause the impedance mismatch between the LED and the post trans-impedance
amplifier. The optical power dependent impedance of the LED is well fitted by a
modified dispersive carrier transport model for inorganic semiconductors. The
bandwidth of the LED-LED visible light communication link is further shown to
decrease with the optical power received by the LED. This leads to a trade-off
between link bandwidth and SNR, and consequently affects the choice of the
proper dada modulation scheme.Comment: 9 pages, 9 figures, submitted to Optics Expres
Phototransistor-like Light Controllable IoT Sensor based on Series-connected RGB LEDs
An IoT optical sensor based on the series-connected RGB LEDs is designed,
which exhibits the light-controllable optical-to-electrical response like a
phototransistor. The IoT sensor has the maximal AC and DC responsivities to the
violet light mixed by blue and red light. Its responsivity to the blue light is
programmable by the impinging red or green light. A theoretical model based on
the light-dependent impedance is developed to interpret its novel
optoelectronic response. Such IoT sensor can simultaneously serve as the
transmitter and the receiver in the IoT optical communication network, thus
significantly reduces the system complexity.Comment: 4 pages, 2 figures, submitted to Electronic Device Letter