Avalanche photodiode bias circuit and optical transmission equipment having the circuit

The utility model discloses an avalanche photodiode (APD) biasing circuit and an optical transmission device with the circuit, comprising an input end of a direct current supply, a PWM (Pulse Width Modulation) boost converter, current-storing inductance and a doubling circuit, wherein, one end of the current-storing inductance is connected with the input end of a direct current supply, on one hand, the other end is connected with the PWM output end of the PWM boost converter, and on the other hand, the other end is connected with the doubling circuit; under the control of PWM signals outputted by the PWM boost converter, after the voltage outputted by the current-storing inductance is boosted and processed, on one hand, the doubling circuit is connected with the bias voltage end of the avalanche photodiode through the output end thereof, and on the other hand, the doubling circuit is connected with the feedback end of the PWM boost converter through a sampling circuit. The APD biasing circuit controls the voltage booster circuit to work by adopting a PWM mode, thereby not only enlarging the input voltage range, but also being capable of providing reliable and stable bias working voltage for APD devices. The circuit has simple adjustment, easy control, convenient mass production and conversion.