A precise determination of laser beam position or laser illuminated object position using quadrant photodiode can be made in different arrangements signal processing. In this paper two arrangements for displacement signals processing are compared. New relationships of displacement signal using four (2+2) and only two (1+1) opposite sectors on quadrant photodiode are derived. Sensitivity of position sensitive devices with quadrant photodiode is analyzed. The sensitivity is higher for (1+1) than (2+2) configuration, for equal parameters. This is an important result in designing of the command and control devices in laser guidance systems.