Time of Flight Analog Correlator for Distance Measurement with SPADs
An analog time of flight correlator designed in a 150 nm LFoundry CMOS process, capable of correlating photon pulses with an input clock for the use with single-photon avalanche diodes (SPADs) is presented. This correlator will allow highly sensitive and high precision indirect time of flight (iTOF) distance measurement with modulation frequencies up to 1 GHz and a distance resolution of 3 mm and 1.3 mm for a total measurement time of only $4\ \mu\mathrm{s}$ and $40\ \mu\mathrm{s}$, respectively. Additionally long integration times are possible, which guarantee operation with high background-to-signal-ratios (BSR). The small size and low power consumption of less than 1 mW allow the use of many correlators on a single chip. Two correlators and a quenching circuit are integrated on a chip with a size of $1.5 \times 1.3\ \text{mm}^{2}$. The size of a single correlator is $225 \times 143\ \mu\mathrm{m}^{2}$.