Impedance, modulation response and equivalent-circuit of 650 nm surface emitting type light-emitting diode for POF data-links

Abstract The basic electrical equivalent circuit of an AlGaInP based 650 nm ring-LED proposed for plastic-optical fiber data-links is derived. The LED's modulation bandwidth is found to be 65 MHz at a link average driving bias current of 35 mA. The LED's modulation response is measured and shows an open-eye diagram for 156 Mbps non-return-to-zero (NRZ), pseudo-random signals with and without a peaking circuit, respectively.