PETsys is developing a new version of the TOFPET 2 ASIC optimized for LIDAR applications. The new ASIC is a 64-channel chip designed in standard CMOS 130 nm technology. It uses a combination of discriminators for best timing and background rejection. All thresholds are configurable to a value that can be different for each channel. Every time one of the 64 channels exceeds the trigger threshold a record is created giving the channel number, the time and the charge of the event. Activity in one channel does not cause any dead-time on the other channels.

Flyer TOFLAR ASIC for LIDAR.pdf

The main features of the PETsys LIDAR ASIC are:

1. Excellent time resolution using time interpolation between clock cycles based Successive Approximation (SAR) ADC of 10 bits and 10 ps time binning. This will allow a time resolution better than 20 ps (rms) for large pulses and of better than 100 ps (rms) for Single Photon pulses.
2. Large dynamic range: The ASIC measures SiPM pulses in the range from 1 photon to 10⁴ photons (SiPM gain =10⁶).
3. The ASIC has noise filtering and baseline stabilization. This reduces the influence of SiPM dark noise and eliminates the baseline fluctuations due to pileup of closely spaced events.
4. High data rate. The ASIC accepts events at an average input rate of 1 M events/s per channel.
5. The ASIC is able to store the timing and amplitude information of 32 shortly spaced consecutive events. Depending on the SiPM type, pulse filtering allows discrimination of pulses separated by as little as 5 ns.
6. Amplitude measurement. Pulse amplitude measurement is performed in the full input dynamic range using Time Over Threshold and/or Charge to Amplitude Converter. The ASIC is also equipped with an on-chip amplitude calibration pulse generator with programmable amplitude.
7. Precise internal voltage and current references will minimize the dependence on Process, Voltage and Temperature variations.
8. Clock frequency 200 MHz

This development started because several customers expressed interested in using the PETsys TOFPET2 ASIC in LIDAR applications. One customer said: "We reviewed a wide range of TDC/QDC devices and the TOFPET2C was the best. The level of integration in the TOFPET2C was unmatched (an area where many devices proved inadequate was output bandwidth). The large output bandwidth of the TOFPET2C is required for LIDAR applications (and this would warrant further review if spinning the TOFPET2C for automotive LIDAR applications).”