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In this paper, an optoelectronic integrated receiver chip including five PIN photodiodes will be presented. A large 200-μm diameter photodiode connected to a high-speed transimpedance amplifier works as a 3-Gb/s receiver for optical wireless communication. Four surrounding photodiodes allow for the adjustment of the incoming laser ray. The complete chip was realized in a silicon 0.35-μm BiCMOS technology to benefit from the available intrinsic zone in this technology. Due to this intrinsic zone and an antireflection coating, the responsivity reaches a value of more than 0.5 A/W for wavelengths from 630 to 760 nm. Furthermore, the capacitance of the center photodiode is less than 0.6 pF for reverse bias voltages larger than 3 V. For proof of concept, a steerable and adjustable light source was built based on a micro-electro-mechanical system mirror, on a focusing unit, and on a direct modulated vertical cavity surface emitting laser with a wavelength of 680 nm. The complete system is capable of establishing a 3-Gb/s data transfer over a distance of 19 m at a BER of <10 −9 , and over a distance of 18 m at a BER of <10 −12 .

The transient photocurrent response of a vertically stacked triple pn junction structure, which can detect three different colours simultaneously, is investigated. The triple pn junction structure is designed based on the effect that the penetration depth in silicon depends on light wavelength. To increase the bandwidth of optical sensor systems the transient photocurrent response is a critical parameter. The transient response is measured by applying three different light wavelengths to this triple junction structure. This triple pn junction structure is fabricated in a 0.6 µm BiCMOS technology using a p−p+ epitaxial wafer without any process modification. Based on the measurement results, it can be concluded that this triple pn junction structure can be applied to optical sensors without optical filters and the total data rate of this structure can reach up to 100 Mbit/s.

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