A new readout/driver circuitry for an optical vibration sensor

Abstract

This work presents research results on designing the drive and readout circuits for a newly-developed optical vibrations sensor. Tes sensor consists of organic light-emitting diodes (OLEDs) and photodetectors (OPDs) and micro-structure to realize the function of vibration sensing. Proper operations of OLEDs and OPDS needs a driver and a readout circuit, respectively. A driver circuit is designed for driving and controlling OLED light; also, a readout circuit is designed to acquire current signal from OPD and then converts it to digital signals by an analog-to-digital converter (ADC). In addition to readout circuit, a front-end amplifier called transimpedance amplifier (TIA) is designed for converting the output current of the OPDs. The TIA is followed by an IA and LPF for better signal quality before a SAR ADC designed for converting the vibration amplitude to digits. The resolution of 10-bit ADC sub-circuit is 1.95mV/LSB. It is suitable for OPD current output. Moreover, a pulse width modulation (PWM) driver circuit which is designed with frequency output 200 KHz is suitable for driving OLED. The proposed circuit is fabricated by TSMC 0.35-mu m CMOS process where the area is 4.5 mm2 for the whole chip while power consumption is 7.808 mW.