Spectroscopic quantum imaging using pixel-level ADCs in semiconductor-based hybrid pixel detectors

This thesis describes the design of a microelectronic system that can be used to build a spectroscopic imaging system, in particular a spectroscopic quantum imaging using pixel-level ADCs in semiconductor-based hybrid pixel detectors. In such a system the signal generated in the sensor by a photon interaction is electronically processed to obtain a measurement of the energy deposited by the photon. This measurement is expressed as a digital value and read from the pixel by the appropriate circuitry located in the periphery of the chip. The digital data corresponding to the measurement (energy of the photon and pixel address in the imaging array) is then read from the chip by an external data acquisition system for further processing or visual presentation

Design of pixel-level ADCs for energy-sensitive hybrid pixel detectors

Single-photon counting hybrid pixel detectors have shown\ud to be a valid alternative to other types of X-ray imaging\ud devices due to their high sensitivity, low noise, linear behavior\ud and wide dynamic range. One important advantage of these\ud devices is the fact that detector and readout electronics are\ud manufactured separately. This allows the use of industrial\ud state-of-the-art CMOS processes to make the readout\ud electronics, combined with a free choice of detector material\ud (high resistivity Silicon, GaAs or other). By measuring not\ud only the number of X-ray photons but also their energies (or\ud wavelengths), the information content of the image increases,\ud given the same X-ray dose. We have studied several\ud possibilities of adding energy sensitivity to the single photon\ud counting capability of hybrid pixel detectors, by means of\ud pixel-level analog-to-digital converters. We show the results of\ud simulating different kinds of analog-to-digital converters in\ud terms of power, area and speed

Pixel-level Analog-To-Digital Converters for Hybrid Pixel Detectors with energy sensitivity

Single-photon counting hybrid pixel detectors have shown to be a valid alternative to other types of X-ray imaging devices due to their high sensitivity, low noise, linear behavior and wide dynamic range. One important advantage of these devices is the fact that detector and readout electronics are manufactured separately. This allows the use of industrial state-of-the-art CMOS processes to make the readout electronics, combined with a free choice of detectors material (high resistivity Silicon, GaAs or other). By measuring not only the number of X-ray photons but also their energies (or wavelengths), the information content of the image increases, given the same X-ray dose. We have studied several possibilities of adding energy sensitivity to the single photon counting capability of hybrid pixel detectors, by means of pixel-level analog-to-digital converters. We show the results of simulating different kinds of analog-to-digital converters in terms of power, area and speed

Design of analog-to-digital converters for energy sensitive hybrid pixel detectors

An important feature of hybrid semiconductor pixel detectors is the fact that detector and readout electronics are manufactured separately, allowing the use of industrial state-of-the-art CMOS processes to manufacture the readout electronics. As the feature size of these processes decreases, faster and more complex electronics can be designed and manufactured. Furthermore, most new CMOS processes are optimised for use with digital circuits, making the design of precise analog electronics a difficult task. Hence, the sooner the data is converted to the digital domain, the better the technology can be used. We have studied the possibility of adding energy sensitivity to the single photon counting capability of pixel detectors. To know not only the number of X-ray photons but also their energies (or wavelenghts), will increase the information content of the resulting image, given the same X-ray dose. In order to do this, a small and low power ADC is added to each pixel. We have studied different types of analog-to-digital converters that can be implemented inside the pixel electronics of a pixel detector

Live Demonstration: Front and Back Illuminated Dynamic and Active Pixel Vision Sensor Comparison

The demonstration shows the differences between two novel Dynamic and Active Pixel Vision Sensors (DAVIS). While both sensors are based on the same circuits and have the same resolution (346×260), they differ in their manufacturing. The first sensor is a DAVIS with standard Front Side Illuminated (FSI) technology and the second sensor is the first Back Side Illuminated (BSI) DAVIS sensor

An interface board for the control and data acquisition of the Medipix2 chip

We have designed an interface board between the Medipix2 chip and a general-purpose commercial PCI-based acquisition card, making the Medipix2 fully controllable from a PC. The main component on the board is an FPGA that implements the data transmission between the chip and the PC, as well as a number of internal registers to control the operation of the chip. Besides the FPGA, the board also includes a number of data converters for different purposes, a timing source, power supply regulators to generate the power supply voltage needed by the chip, and some level converters to accommodate the different logic levels at the PC, FPGA and Medipix2 chip. The board has been designed to interface with a chip-board containing a maximum of eight Medipix2 chips. The Medipix2 chips are read out via their serial data interface using the LVDS standard. We will describe the design of the board, its operational characteristics and show how the board has been used to characterize the Medipix2 chip