Readout architecture for fmcw lidar

A method to determine a distance or a velocity of an object, the method comprising:

• receiving a waveform signal corresponding to a target;
• generating a pulse signal from the received waveform signal;
• resetting a primary counter and a reference counter;
• beginning a primary count with the primary counter and a reference count with the reference counter after a first time period since the resetting of the primary counter and the reference counter has elapsed;
• continuing the primary count and the reference count for a second time period;
• retaining a last primary value of the primary counter and a last reference value of the reference counter;
• calculating a ratio of the last primary value to the last reference value;
• and
• multiplying a reference distance by the ratio.

A non-transitory computer readable medium implemented on a readout integrated circuit of a frequency-modulated continuous wave (FMCW) LiDAR system, the non-transitory computer readable medium having computer code that, when executed on a processor, implements a method of determining a distance or a velocity of an object, the method comprising:

• receiving a waveform signal corresponding to a target;
• generating a pulse signal from the received waveform signal;
• resetting a primary counter and a reference counter;
• beginning a primary count with the primary counter and a reference count with the reference counter after a first time period since the resetting has elapsed;
• continuing the primary count and the reference count for a second time period;
• retaining a last primary value of the primary counter and a last reference value of the reference counter;
• calculating a ratio of the last primary value to the last reference value;
• and
• multiplying a reference distance by the ratio.