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

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

Keywords

Timeofflight, optical distance measurement, OEIC, correlation, PIN photodiode,

Abstract

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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