Active Bridge-Correlator Circuit with Integrated PIN Photodiode for Optical Distance Measurement Applications

K. Oberhauser, G. Zach, and H. Zimmermann (Austria)


Time-of-flight, optical distance measurement, OEIC, correlation, PIN photodiode,


The presented active bridge-correlator circuit is implemented as an opto-electronic integrated circuit (OEIC) in a 0.6µm BiCMOS technology. The distance measurement principle is based on the determination of the phase-shift between a received optical square-wave signal and an electrical modulation signal. The integrated high-speed PIN photodiode and the newly developed active correlator circuit performing the electronic correlation are implemented on a single chip. By using the active structure the sensitivity and the fill factor are greatly improved compared to [1]. For an optical active area of Apd = 75×125µm2 a very high fill factor of ηfill = 61% is reached. The sensor is capable of measuring distances up to sd = 3.4m with an optical transmitted power of Popt = 1mW at a wavelength of λ = 650nm. The linearity error is slin = ±18mm and the standard deviation is less than σd = 14mm over the full measurement range. Non modulated background light is inherently suppressed by the switched-capacitor setup.

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