Lidar receiving apparatus, lidar system and laser ranging method

A lidar system, comprising:

• a lidar transmitting apparatus configured to transmit a laser signal and a lidar receiving apparatus, wherein the lidar receiving apparatus comprises:
• a photodetector, which is configured to receive a reflected laser signal and to convert the reflected laser signal into a current signal when a bias voltage of the photodetector is greater than a breakdown voltage of the same;
• a reference photodetector, which is in a light-shielded state, and is connected in parallel with the photodetector;
• and
• a ranging circuit, which is connected with the photodetector, and configured to control the bias voltage applied to the photodetector according to a predefined rule,
• wherein the predefined rule comprises:
• at a receiving time of a stray reflected signal, the bias voltage of the photodetector is smaller than the breakdown voltage;
• and the receiving time of the stray reflected signal is a time at which a transmitted laser signal reaches the photodetector through a stray light path other than a ranging light path, and is correlated to a preset flight time of the stray reflected signal, and
• wherein the ranging circuit comprises:
• a cancelling and trans-impedance amplifying circuit, which is connected with the photodetector and the reference photodetector, respectively, and configured to perform cancellation and trans-impedance amplification on both current signals output from the photodetector and the reference photodetector, and output voltage signals obtained after the cancellation and the trans-impedance amplification are performed, wherein the current signal output from the reference photodetector is positively correlated to the bias voltage applied to the reference photodetector;
• and
• a second processing circuit, which is connected with the cancelling and trans-impedance amplifying circuit, and configured to calculate the distance data according to the voltage signals obtained after the cancellation and the trans-impedance amplification are performed.