Analysis and Design of Analog Front-end Circuitry for Avalanche Photodiodes (APD) and Silicon Photo-multipliers (SiPM) in Time-of-flight Applications

This thesis reports the analysis and design of analog front-end circuitry for reading out signals from avalanche photodiodes (APD) or silicon photomultiplier (SiPM) in time-of-flight (ToF) applications. An integrated circuit was designed using AMS SiGe 0.35 um BiCMOS process. The chip measured 2 mm x 2 mm (2000 umx2000 um). The chip mainly contains the following circuits: an APD with photoactive area measuring 24 umx24 um, an SiPM with 8x8 APDs with 236 k ohm quench resistors, a transimpedance amplifier (TIA), a comparator and a R-2R digital to analog converter (DAC). The TIA is based on the shunt-shunt feedback topology. The TIA gain can be digitally set using two input bits to range from -0.9 k ohm to -14.44 k ohm with a bandwidth ranging from 93 MHz to 113 MHz. Photodetector capacitance on TIA input reduces the bandwidth. The maximum positive input current dynamic range of the TIA is 294 uA. The TIA consumes a power of 7.1 mW. The comparator has a maximum speed of 265 MHz with input sensitivity down to 50 uV and consumes about 6.6 mW of power. The R-2R DAC has a 10-bit resolution with maximum differential nonlinearity (DNL) and integral nonlinearity (INL) of -0.14 LSB and -0.09 LSB respectively with no load. Design considerations for all the blocks are given and simulation results are compared to hand calculations. The TIA, comparator and DAC are connected as a system and the simulation is functional. Using this system to implement a time-of-flight LiDAR (light detection and ranging), a range resolution down to 1.2 m (3.9 ft) can be achieved with photodetector capacitance of 0.1 pF

Local Positioning System Using Flickering Infrared LEDs

International audienceA minimalistic optical sensing device for the indoor localization is proposed to estimate the relative position between the sensor and active markers using amplitude modulated infrared light. The innovative insect-based sensor can measure azimuth and elevation angles with respect to two small and cheap active infrared light emitting diodes (LEDs) flickering at two different frequencies. In comparison to a previous lensless visual sensor that we proposed for proximal localization (less than 30 cm), we implemented: (i) a minimalistic sensor in terms of small size (10 cm 3), light weight (6 g) and low power consumption (0.4 W); (ii) an Arduino-compatible demodulator for fast analog signal processing requiring low computational resources; and (iii) an indoor positioning system for a mobile robotic application. Our results confirmed that the proposed sensor was able to estimate the position at a distance of 2 m with an accuracy as small as 2-cm at a sampling frequency of 100 Hz. Our sensor can be also suitable to be implemented in a position feedback loop for indoor robotic applications in GPS-denied environment

Characteristic properties of Planacon MCP-PMTs

A systematic investigation of Planacon MCP-PMTs was performed using 64 XP85002/ FIT-Q photosensors. These devices are equipped with microchannel plates of reduced resistance. Results of a study of their gain stability over time and saturation level in terms of the average anode current are presented. This information allows one to determine the lower limit of the MCP resistance for stable Planacon operation. The spread of the electron multiplication characteristics for the entire production batch is also presented, indicating the remarkably low voltage requirements of these MCP-PMTs. Detection efficiency and noise characteristics, such as dark count rate and afterpulsing level, are also reviewed.Peer reviewe

High Sensitivity Photodetector for Photon-Counting Applications

In the last years, there has been a large development of low-light applications, and many of them are based on photon counting using single-photon detectors (SPDs). These are very sensitive detectors typically with an internal gain. The first candidate SPD was the photomultiplier tube (PMT), reaching a very high gain (~106), but there have been a large development of many other solutions, like solid-state solutions. Among them, single-photon avalanche diodes (SPADs) have been used in spectroscopy, florescence imaging, etc., particularly for their good detection efficiency and time resolution (tens of picoseconds). SPADs have been developed in silicon and III–V materials, for the NIR wavelength range. SPADs can be used as single high-performance pixels, or in arrays. SPAD arrays have imaging capabilities, with high sensitivity. Another kind of array is the silicon photomultiplier (SiPM), where all the pixels are connected to a common anode and a common cathode. SiPMs are used in nuclear medicine, physics experiments, quantum-physics experiments, light detection and ranging (LIDAR), etc., due to their high detection efficiency combined with large sensitive areas, and high dynamic range. SiPMs with many small cells present several advantages and nowadays the SPAD pitch can be reduced down to 5 μm

A Focal Plane Array and Electronics Model for CMOS and CCD Sensors in the AFIT Sensor and Scene Emulation Tool (ASSET)

Electro-optical and infrared (EO/IR) sensor models are useful tools that can facilitate understanding a system\u27s behavior without expensive and time-consuming testing of an actual system. EO/IR models are especially important to the military industry where truth data is required but is sometimes impractical to obtain through experimentation due to expense or difficulties in procuring hardware. This work describes implementation of a focal plane array (FPA) model of charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) photodetectors as a component in the Air Force Institute of Technology (AFIT) Sensor and Scene Emulation Tool (ASSET). The FPA model covers conversion of photo-generated electrons to voltage and then to digital numbers. It incorporates sense node, source follower, and analog-to-digital converter (ADC) components contributing to gain non-linearities and includes noise sources associated with the detector and electronics such as shot, thermal, 1/f, and quantization noise. This thesis describes the higher fidelity FPA and electronics model recently incorporated into ASSET, and it also details validation of the improved model using EO/IR imager data collected with laboratory measurements. The result is an improved model capable of generating realistic synthetic data representative of a wide range of systems for use in new algorithm development and data exploitation techniques supporting a broad community of academic, commercial, and military researchers

Design, Layout, and Testing of Sige APDs Fabricated in a Bicmos Process

This Thesis is concerned with the design, layout, and testing of avalanche photodiodes (APDs). APDs are a type of photodetector and, thus, convert light signals into electrical signals (current or voltage). APDs can be fabricated using silicon (Si). In this Thesis, however, three integrated circuit (IC) chips containing various silicon-germanium (SiGe) APDs with different sizes, structures, and geometries were designed, laid out, and fabricated using the Austriamicrosystems (AMS) 0.35μm SiGe BiCMOS (S35) process. This was done in order to compare SiGe APDs to Si only APDs and investigate the hypothesis that SiGe APDs are capable of detecting longer wavelengths than Si only APDs. This is due to the smaller band gap energy associated with SiGe compared to that of Si. The different SiGe APDs were tested and found to, indeed, have the capability of detecting slightly longer wavelengths than Si APDs. A 5μm x 5μm SiGe APD and 24μm x 24μm SiGe APD were found to have a spectral peak at 500nm and a cutoff wavelength (λc) of 1180nm compared to 480nm and 1100nm, respectively, for a 10μm x 10μm Si APD. The 24μm x 24μm SiGe APD was also found to have a responsivity of 0.34 A/W at 500nm and quantum efficiency (QE) of 85% at 450nm. APDs differ from traditional photodiodes in that they possess an internal avalanche gain and, thus, produce a larger electrical signal than a traditional photodiode for the same amount of incident light. All photodiodes produce an undesired electrical signal, called dark current, even in a dark state with no light signal incident on the photodiode. Therefore, the gain and dark current associated with each of the fabricated APDs was also measured in order to determine the characteristics of the different SiGe APD variants. The 5μm x 5μm and 24μm x 24μm SiGe APDs have a zero bias (0V) dark current of 3pA and 5pA, respectively, compared to 3pA for the 10μm x 10μm Si APD. The 5μm x 5μm and 24μm x 24μm SiGe APDs and the 10μm x 10μm Si APD also have gains of 88,000 (98dB), 1390 (63dB), and 1000 (60dB), respectively

A Low-Power Optoelectronic Characterizer for CubeSat: LOCC and III-V Nitride Based LEDs

III-V semiconductor materials exhibit robustness and natural hardness when exposed to ionizing radiation and temperature swings. With these characteristics in mind, III-V Nitride Light Emitting Diodes (LEDs) are ideal devices for space-based applications and missions. The effects of ionizing radiation on optoelectronic devices comprised of III-V materials have been studied, but results have been obtained through experiments performed in terrestrial laboratories. While these laboratory tests may lend insight into device lifetimes, performance degradation, etc., they are no substitute for similar measurements and characterization performed in space.;Interest in small satellite applications have grown over the past decade. These solutions range from Earth imaging to communication networks. Small satellites provide a unique opportunity to gain an understanding of the reliability and operational characteristics of III-V based materials and other semiconductor devices while exposed to the environment of space. To meet the constraints of the small satellite, a Low-powered Optoelectronic Characterizer for CubeSat (LOCC) has been developed in PC/104 form, measuring 3.6 by 3.8 inches. LOCC performs current-voltage and electroluminescent measurements of LEDs while in space. The LOCC system is designed using low-power integrated circuits that can supply over 100 mA of current to LEDs while maintaining low power of 3.2W under operation.;This thesis presents the design, implementation, and control of the LOCC system. This includes system block diagrams, printed circuit board layouts, interfacing, firmware, and software. Additionally, the resulting current-voltage measurements, required wattage, and required data storage are presented to illustrate functionality. This instrumentation enables the study of optoelectronic devices in space, allowing future research to focus on producing radiation hard light emitting devices that can operate in environments with reduced shielding against ionizing radiation while maintaining device reliability

Development of ASIC for SiPM sensor readout

L'abstract è presente nell'allegato / the abstract is in the attachmen

Control circuits for avalanche photodiodes

Avalanche Photodiodes (APDs) have been used in a wide range of low light sensing applications such as DNA sequencing, quantum key distribution, LIDAR and medical imaging. To operate the APDs, control circuits are required to achieve the desired performance characteristics. This thesis presents the work on development of three control circuits including a bias circuit, an active quench and reset circuit and a gain control circuit all of which are used for control and performance enhancement of the APDs. The bias circuit designed is used to bias planar APDs for operation in both linear and Geiger modes. The circuit is based on a dual charge pumps configuration and operates from a 5 V supply. It is capable of providing milliamp load currents for shallow-junction planar APDs that operate up to 40 V. With novel voltage regulators, the bias voltage provided by the circuit can be accurately controlled and easily adjusted by the end user. The circuit is highly integrable and provides an attractive solution for applications requiring a compact integrated APD device. The active quench and reset circuit is designed for APDs that operate in Geiger-mode and are required for photon counting. The circuit enables linear changes in the hold-off time of the Geiger-mode APD (GM-APD) from several nanoseconds to microseconds with a stable setting step of 6.5 ns. This facilitates setting the optimal `afterpulse-free' hold-off time for any GM-APD via user-controlled digital inputs. In addition this circuit doesn’t require an additional monostable or pulse generator to reset the detector, thus simplifying the circuit. Compared to existing solutions, this circuit provides more accurate and simpler control of the hold-off time while maintaining a comparable maximum count-rate of 35.2 Mcounts/s. The third circuit designed is a gain control circuit. This circuit is based on the idea of using two matched APDs to set and stabilize the gain. The circuit can provide high bias voltage for operating the planar APD, precisely set the APD’s gain (with the errors of less than 3%) and compensate for the changes in the temperature to maintain a more stable gain. The circuit operates without the need for external temperature sensing and control electronics thus lowering the system cost and complexity. It also provides a simpler and more compact solution compared to previous designs. The three circuits designed in this project were developed independently of each other and are used for improving different performance characteristics of the APD. Further research on the combination of the three circuits will produce a more compact APD-based solution for a wide range of applications