A CMOS infrared optical signal processor for remote control

A CMOS infrared OSP (optical signal processor) for remote control is presented in this paper. The infrared OSP has been fabricated in the past using bipolar or BiCMOS processes because the noise performance of BJT devices is better than that of MOS devices. In this paper, we design a low noise CMOS OSP using transient noise simulation. The designed OSP is composed of a pre-amplifier with variable gain, a band-pass filter, a noise level detector, and an output signal shaper. A pre-amplifier converts the current signal from the photodiode to a voltage signal, and amplifies the converted voltage signal with variable gain controlled by the noise level. A band-pass filter attenuates the noise signal from internal devices or external light sources. A noise level detector detects the noise level of the filtered signal and controls the gain of the variable gain amplifier. The OSP output signal is generated from the signal shaper. The designed OSP is fabricated using a 0.5 μm CMOS process and it occupies the smallest size (0.9 mm×0.7 mm) among the present OSPs. It consumes a low power of 1.5 mW at a 3 V single supply.