Threshold Detection Method, Module and Readout Integrated Circuit Layer for LIDAR Time of Flight System Using Differentiated Gaussian Signal

1 . A method for determining the range of a target surface in a LIDAR system comprising the steps of:

imaging the target surface with an electromagnetic illumination signal,

receiving a reflected echo of the illumination signal as a return signal having a peak amplitude,

differentiating the return signal to define a differentiated signal having a signal level crossing point representative of the peak amplitude, and,

comparing the signal level crossing point to a predetermined threshold level to determine the range of the target surface.

2 . The method of claim 1 wherein the return signal is a Gaussian signal.

3 . The method of claim 1 wherein the return signal is differentiated using high pass filter circuitry means.

4 . A LIDAR photo-detector module comprising:

a photo-detector array comprising a plurality of photo-detectors for detecting photons and generating output signals in response to photon detection,

a plurality of readout electronics integrated circuit chips,

each of the readout electronics integrated circuit chips comprising a plurality of channels for receiving and processing the output signals generated by the photo-detector array, wherein the plurality of readout electronics integrated circuit chips are arranged in a stacked configuration wherein said photo-detector array is bonded to a lateral surface of the stacked configuration perpendicular to the stacked configuration and connected to the plurality of channels via a plurality of connections arranged on the lateral surface of the stacked configuration, and,

wherein at least one of the readout integrated circuit chips comprises differentiating circuit means configured to output a differentiated signal having a signal level crossing point representative of the peak amplitude of a return signal.

5 . The photo-detector module of claim 4 wherein the received signal is a Gaussian signal.

6 . The photo-detector module of claim 4 wherein received signal is differentiated using high pass filter circuitry means.

7 . A LIDAR readout integrated circuit comprising:

primary differentiating circuit means for performing a first differentiation of an output signal of a photo-detector array in response to a laser echo return from a target surface to define a primary differentiated signal,

amplifier circuit means for amplifying the primary differentiated signal,

secondary differentiating circuit means for performing a secondary differentiation of the amplified primary differentiated signal for identifying the peak amplitude of the amplified primary differentiated signal,

analog-to-digital conversion circuitry for converting the secondary output signal to a digitized value, and,

a FIFO register for receiving and storing the digitized value.