This results in the poor conversion efficiency of phototransistors. Also, the material used in the phototransistor may limit its voltage handling capability for instance, silicon cannot handle over 1,000 Volts and the efficiency of phototransistors decreases when an electromagnetic field interferes within the operation region. Phototransistors do not have a particularly good high frequency response, which is restraining the growth of the market to some extent. Phototransistors, as compared to other alternatives such as avalanche photodiodes, offer several advantages, such as lower noise levels. Further, the increasing use of phototransistors in the lighting industry is also surging the demand for this market as phototransistors are largely used in ambient light sensing and street light sensing. The increasing adoption of sensors has been driving the phototransistor industry as phototransistors are used as position sensors. Phototransistor Market: Drivers and Challenges In such cases, phototransistors provide a lower cost alternative. Signal of a photodiode can be amplified through external circuitry but it is not considered to be cost effective. As many of the applications demand for high output which is not possible for a photodiode to work with, so the phototransistors are used for the same.

The gain for a phototransistor has a generalized range from 100 to over 1500. This combination had a particularly specific task to overcome a major limitation of photodiode which was unity gain. The phototransistor were realized as a photodiode whose output current is fed to the base of a transistor. Phototransistors are considered as the photodiode attached to an amplifiers that are integrated on a single silicon chip. The other features to consider for the phototransistors were its relatively less cost, simple and small structure. One of the other points for choosing the phototransistor over others was its compatibility with most visible or near infrared light sources including IREDs, neon bulbs, fluorescent bulbs, incandescent bulbs, and other, Also, it gave faster results with almost instantaneous output. Current parameter not being the only reason, but also the voltage generation which was not like the photoresistors, which became a point for the selection of phototransistors over others. As the phototransistors produce higher current than the photodiodes, they are preferred for many applications.

Phototransistors download free