Garmin LIDAR-Lite v1 Silver Label Operating Manual page 16

1. An 8­bit microcontroller provides system control and communications. It contains an I2C slave
peripheral.
2. A 500 MHz sampling clock and an associated sampler capture the logic state of the external
comparator and convert the data into a slower speed 125 MHz four bit word which is sent to a
correlation processor.
3. A correlation processor stores the incoming signal and performs a correlation operation against a
stored signal reference with optical burst reception and stores the result in the correlation memory
with data points every 2 ns.
4. A transmit signal generator produces an encoded signal waveform with an overall duration of 500 ns
that consists of a varying interval pattern of ones and zeroes. These outgoing signal pulses occur at
a 20 KHz repetition rate and become either the reference signal or outgoing signal pulse depending
on the state of the transmitter.
Optical Transmitter and Receiver
The optical transmitter and receiver have been designed around the requirements of our signal­processing
algorithm. The transmitter produces optical pulse bursts using signal patterns generated by the SPC. When
an optical reference signal is desired, a separate reference transmitter is enabled and driven with the signal
pattern using a reference fed to the optical receiver. The reference transmitter has been designed to match
the delay and signal shape produced by the higher power signal transmitter. The signal transmitter can
drive a variety of optical sources ranging from high speed LEDs, higher power VCSEL laser or much higher
power pulsed laser diodes. For the LIDAR­Lite module, the signal transmit driver drives a T1­3/4 plastic
packaged laser diode with a three­amp peak, 50% average duty cycle modulation over a burst duration of
500 ns. The driver has a capability to drive sources at up to 6 A using an external DC power supply.
Parameter
Bandwidth 50 MHz, on­off modulation, arbitrary pattern
Burst Time/rate 500 ns/20KHz
Typology High side current source (programmable), low­side differential current steering
Reference Channel 1 A peak (nominal setting)
Signal Channel 3 A peak (nominal setting)
Transmit Power Control 16 steps each Channel
Rise/fall 4 ns
The receiver incorporates a state­of­the­art low­noise preamplifier that is coupled to either a PIN photodiode
or, optionally, an avalanche photodiode (APD). When using the higher performance APD, an external
regulated high voltage bias voltage is needed. The APD is used to increased system sensitivity allowing
either increased operating range or reduced measurement times. Before reaching the high­speed digital
LIDAR­Lite v1 "Silver Label" Manual​ , Updated: 08/13/15
Transmitter specification