Integrated Electro-Optical PLL for Linear FMCW Modulation of a Tunable Laser

An integrated electro-optical PLL modulates the frequency of a tunable laser for use in frequency-modulated continuous-wave (FMCW) lidar. The frequency of the laser has a 90kHz triangular pattern with 120GHz peak-to-peak excursion. The proposed lidar can perform 180k range measurements per second. The RMS depth precision is 8µm at distances of ±5cm from the range baseline. The range window is 1.4m, with a precision of 4.2mm at the edges of the window. The photonic circuitry, including input light couplers, waveguides, and photodiodes, is realized on a 3mm×3mm silicon-photonic chip. The 0.18µm CMOS ASIC of the same area comprises the front-end transimpedance amplifier, analog electro-optical PLL, and digital control circuitry consuming 1.7mA from a 1.8V supply and 14.1mA from a 5V supply. The two chips are integrated using through-silicon-vias implemented in the silicon-photonic chip.