A Monolithic Low Power Pulsed Optical Encoder

This paper presents a low-power 14-bit monolithic absolute optical encoder with threshold programming capabilities. The chip was fabricated in standard 0.8 um CMOS technology with a die area of 6 sqmm including pads. Experimental results shown the correct functionality of the circuit with a minimum optical input power of 300uW/cm2. The sensor exibits a total power consumption of 5 mW at 5 V, which is a very good value if compared with consumption of commercial devices. It has been shown that the adopted signal readout technique has advantages of high scalability. Forthermore, the photosensor dimensions used in this chip can be further reduced without affecting the sensor performance. In this case, the main limitations will probably derive from the tolerance of the mechanical alignments among sensor, optical collimator, coded disk and LE