Lidar sensor with high dynamic range pulse receiver

1 . A lidar sensor, comprising:

an optical transmitter configured to generate a pulse of light;

an optical receiver configured to receive the pulse of light generated by said optical transmitter and reflected off an object in a field of view, said optical receiver including:

a photodetector configured to generate a photocurrent pulse corresponding to the received pulse of light; and

a receiver circuit electrically connected to said photodetector;

said receiver circuit including a current mirror providing multiplication of the photocurrent pulse provided by said photodetector; and

said receiver circuit configured to convert the photocurrent pulse to a voltage pulse and provide the voltage pulse as an output;

a shunt MOSFET, which conducts a portion of said photocurrent pulse when said photocurrent pulse exceeds a threshold;

wherein the shunt MOSFET has a source electrically connected to the receiver circuit output, a gate electrically connected to a bias voltage, and a drain electrically connected to a constant potential;

a resistor electrically connected between the receiver circuit output and the constant potential and across the shunt MOSFET;

a capacitance electrically connected between the receiver circuit output and the constant potential and across the shunt MOSFET;

wherein a first value of the resistor is selected according to a desired amplitude and a desired decay time constant of the voltage pulse, and a second value of the capacitance is minimized.

2 . The lidar sensor as set forth in claim 1 , wherein said current mirror includes a first metal-oxide-semiconductor field-effect transistor (“MOSFET”) and a second MOSFET, wherein each said MOSFET includes a gate electrically connected to said photodetector, said first MOSFET includes a drain electrically connected to said photodetector, and each said MOSFET includes a source electrically connected to a constant potential.

3 . The lidar sensor as set forth in claim 2 , wherein said optical receiver further includes a current source electrically connected to said drain of said first MOSFET.

4 . The lidar sensor as set forth in claim 2 , wherein said second MOSFET includes a drain electrically connected to said receiver circuit output.

5 . The lidar sensor as set forth in claim 2 , wherein said current mirror is further defined as a first current mirror and said receiver circuit further includes a second current mirror electrically connected to said first current mirror.

6 . The lidar sensor as set forth in claim 5 , wherein said second current mirror includes a third MOSFET and a fourth MOSFET, wherein each MOSFET includes a gate electrically connected to a drain of said second MOSFET, each MOSFET includes a source electrically connected to a constant potential, and a drain of said third MOSFET electrically connected to a drain of said second MOSFET.

7 . The lidar sensor as set forth in claim 6 , wherein said fourth MOSFET includes a drain electrically connected to said receiver circuit output.

8 . The lidar sensor as set forth in claim 1 , wherein said shunt MOSFET has a gate and a drain both electrically connected to said receiver circuit output and a source electrically connected to a constant potential.

9 . The lidar sensor as set forth in claim 1 , further comprising a PN junction having a P-type terminal electrically connected to said photodetector and an N-type terminal electrically connected to a constant potential, wherein said PN junction conducts a portion of said photocurrent pulse when said photocurrent pulse exceeds a threshold.

10 . The lidar sensor as set forth in claim 1 , further comprising a voltage buffer having an input and an output with said input electrically connected to said output of said receiver circuit.

11 . The lidar sensor as set forth in claim 10 , further comprising a servo loop circuit electrically connected to said output of said receiver circuit and said output of said voltage buffer.

12 . The lidar sensor as set forth in claim 11 , wherein said servo loop circuit includes an amplifier having a first input electrically connected to said output of said voltage buffer, a second input electrically connected to a reference voltage, and an output electrically connected to a gate of a fifth MOSFET, wherein a drain of said fifth MOSFET is electrically connected to an input of said voltage buffer.

13 . A method of operating a lidar sensor, comprising:

generating a pulse of light with an optical transmitter;

receiving the pulse of light generated by the optical transmitter and reflected off an object in a field of view with an optical receiver;

generating a photocurrent pulse corresponding to the received pulse of light with a photodetector of the optical receiver;

multiplying the photocurrent pulse provided by the photodetector with a current mirror;

converting the photocurrent pulse to a voltage pulse; and

providing the voltage pulse as an output;

wherein the converting and providing comprises conducting a portion of the photocurrent pulse with a shunt MOSFET when said photocurrent pulse exceeds a threshold, wherein the shunt MOSFET has source electrically connected to a receiver circuit output, a gate electrically connected to a bias voltage, and a drain electrically connected to a constant potential, wherein a resistor is electrically connected between the receiver circuit output and the constant potential and across the shunt MOSFET and a capacitance is electrically connected between the receiver circuit output and the constant potential and across the shunt MOSFET, wherein a first value of the resistor is selected according to a desired amplitude and a desired decay time constant of the voltage pulse, and a second value of the capacitance is minimized.

14 . The method as set forth in claim 13 wherein said step of converting the photocurrent pulse to a voltage pulse comprises applying linear current-to-voltage conversion in response to the photocurrent pulse being less than a threshold value and applying nonlinear current-to-voltage conversion in response to the photocurrent pulse being greater than or equal to the threshold value.