A New Sensing Scheme for Sensitivity Enhancement of Low-Temperature Polycrystalline Silicon Photodetecors

A photo-detector employing a pulse-frequency-modulation (PFM) circuit featuring an adjustable response is realized on a Low Temperature Polycrystalline Silicon (LTPS) panel. A constant-biasing scheme on the photodiode is proposed to overcome the low sensitivity problem in LTPS PIN diodes and greatly improves the output response. Furthermore, an LTPS PIN diode model capable of accurately predicting the characteristics of the detector circuits is established and verified.