A. Polzer

Zero-bias 40Gbit/s germanium waveguide photodetector on silicon

We report on lateral pin germanium photodetectors selectively grown at the end of silicon waveguides. A very high optical bandwidth, estimated up to 120GHz, was evidenced in 10 µm long Ge photodetectors using three kinds of experimental set-ups. In addition, a responsivity of 0.8 A/W at 1550 nm was measured. An open eye diagrams at 40Gb/s were demonstrated under zero-bias at a wavelength of 1.55 µm.

Avalanche Double Photodiode in 40-nm Standard CMOS Technology

This paper investigates a silicon (Si) avalanche double photodiode (ADPD) fabricated in 40-nm standard CMOS technology. Two different types of double photodiodes (DPDs) will be introduced. The first one is a P-well/deep-N-well/P-substrate(PW/DNW/P-substrate) DPD, and the second one is a P+/N-well/P-substrate (P+/NW/P-substrate) DPD. The basic structure of the proposed ADPD is formed by P+/NW and NW/P-substrate junctions in which the avalanche effect occurs at the P+/NW junction. The P+/NW/P-substrate ADPD demonstrates responsivity of 0.84 A/W and a 3-dB electrical bandwidth of 0.7 GHz at 850 nm. For 660 nm, the ADPD shows a responsivity of 0.49 A/W with an electrical bandwidth of 1.8 GHz. For 520 nm, a responsivity of 2.04 A/W and an electrical bandwidth of 1.4 GHz are achieved.

Optical Wireless Communication With Adaptive Focus and MEMS-Based Beam Steering

An optical wireless communication system for an operation with wavelengths detectable by silicon optoelectronic integrated circuits is described. We use direct modulated vertical cavity surface emitting lasers as a transmitter. The field of view of the laser beam is adjusted with an adaptive optical system and aligned with a micro-electro-mechanical system based mirror for beam steering. To receive the modulated laser beam, we develop a receiver chip in 0.35 μm BiCMOS technology. The experimental system shows a 3 Gb/s wireless transmission over a distance of 7 m with a bit-error rate <;10-9 without cost intensive optical components and complex adjustment procedure.

40Gbit/s germanium waveguide photodetector on silicon

We report a Germanium lateral pin photodiode integrated with selective epitaxy at the end of silicon waveguide. A very high optical bandwidth estimated at 120GHz is shown, with internal responsivity as high as 0.8A/W at 1550nm wavelength. Open eye diagram at 40Gb/s was obtained under zero-bias at wavelength of 1.55μm.

Integrated filter-less BiCMOS sensor for RGB-LED color determination

In this work an integrated filter-less BiCMOS based color sensor is presented. It is capable of determining the center wavelength of a monochromatic light source in the visible range. This can be used e.g. to determine the three different light colors of an RGB-LED. The detector is based on the effect that the penetration depth in silicon depends on the wavelength of the incident light. It is built up of three vertically stacked pn junctions - a shallow pn junction as blue light detector, a middle pn junction for sensing the green part of incident light and a deep diode to detect red light. The resulting RGB output is used to discriminate between the three different light colors of an RGB-LED. The sensor was characterized with a sweep able monochromatic light source. The sensor is fabricated in a standard 0.6 µm BiCMOS process without using any additional filter layers. This makes it possible to integrate the sensor with other circuitry into a single chip without process modifications.

A 10Gb/s transimpedance amplifier for hybrid integration of a Ge PIN waveguide photodiode

The presented paper describes a 10 Gbps optical receiver. The transimpedance amplifier (TIA) is realized in standard 0.35 μm SiGe BiCMOS technology. The main novelty of the presented design - investigated in the European Community project HELIOS - is the hybrid connection of the optical detector. The used Germanium photodetector will be directly mounted onto the receiver. A model of the relevant parasitics of the photodetector itself and the novel connection elements (micropads, metal vias and metal lines) is described. Based on this photodetector model an optical receiver circuit was optimized for maximum sensitivity at data rates in the range of 10 Gbps. The design combines a TIA and two limiting amplifier stages followed by a 50 Ω CML-style logic-level output driver. To minimize power supply noise and substrate noise, a fully differential design is used. A dummy TIA provides a symmetrical input signal reference and a control loop is used to compensate the offset levels. The TIA is built around a common-emitter stage and features a feedback resistor of 4.2 Ω. The total transimpedance of the complete receiver chain is in the range of 275 kΩ. The value of the active feedback resistor can be reduced via an external control voltage to adapt the design to different overall gain requirements. The two limiting amplifier stages are realized as differential amplifiers with voltage followers. The output buffer is implemented with cascode differential amplifiers. The output buffer is capable of driving a differential 50Ω output with a calculated output swing of 800mVp-p. Simulations show an overall bandwidth of 7.2 GHz. The lower cutoff frequency is below 60 kHz. The equivalent input noise current is 408 nA. With an estimated total photodiode responsivity of 0.5 A/W this allows a sensitivity of around - 23.1 dBm (BER = 10-9). The device operates from a single 3.3 V power supply and the TIAs and the limiting amplifier consume 32 mA.

High sensitivity 80 Gbps parallel optical receiver for hybrid integrated Ge photodiodes

A high sensitivity 8×10 Gbps parallel integrated optical receiver with transimpedance amplifier followed by limiting amplifier stages and output driver in standard 0.35 µm SiGe BiCMOS technology with low input noise current (407 nA) is presented.

Corrections to “Optical Wireless Communication With Adaptive Focus and MEMS-Based Beam Steering” [Aug 1 2013 1428-1431]

In the above letter [1] , it was assumed that the concomitant angular displacement of the laser beam is equal to the deviation angle of the MEMS mirror. However, according to the reflection law, the angular displacement of the reflected beam is twice the angle through which the mirror has rotated [2] , see Fig. 1 . Therefore, the field of view (FOV)—the sum of the maximum positive and negative deviation angle of the laser ray,—is twice as large as the previously published numbers and the following corrections should be made.

Filterloser, vertikaler, integrierter RGB-Farbsensor in Deep-Sub-µm-CMOS-Technologie

SummaryIn this work a filter-less vertical integrated RGB color sensor fabricated in a 90 nm CMOS technology is presented. The sensor is built up of three vertically stacked pn junctions and uses the effect of different penetration depths in silicon for different wavelengths to determine the color of the incident light.ZusammenfassungIn dieser Arbeit wird ein filterloser, vertikaler, integrierter RGB-Farbsensor, hergestellt in einer 90-nm-CMOS-Technologie, vorgestellt. Der Sensor besteht aus drei vertikal übereinander liegenden pn-Übergängen und nutzt zur Bestimmung der Lichtfarbe die Tatsache, dass Licht unterschiedlicher Wellenlänge unterschiedlich tief in Silizium eindringt.