Auto Power Control Circuit for Laser Diode Driver

An auto laser power control (APC) circuit for optical communication laser diode driver (LDD) is proposed. The APC compensates the fluctuation of (laser diode) LD laser power, maintains the output power at the programmed level. The programmed power level can be set by a resistance outside the chip. The design fabricated in 0.25-mum 1P3M CMOS process. HSPICE simulation shows that the floating region of output laser power is within 0.309% with enabled APC, while the temperature is from -20degC to 70degC. Measured results denote perfect linearity of APC character.