Readout System For Sensors Research Articles

A 16-channel capacitance-to-period converter for capacitive sensor applications

An electronic system able to read out arrays of up to sixteen different capacitive type sensors is presented. The output signal of the readout is a square wave signal, with oscillation period linearly modulated by the respective sensor capacitance under measurement. Components such as charge/discharge current control unit, a multiplexing unit and a bandgap voltage reference are integrated on chip, to obtain a stable and linear readout system for multiple sensors of variable types and capacitance ranges. The ASIC was designed and fabricated in AMS 0.35 μm CMOS technology and was hosted on a PCB together with a supervising microcontroller, which is programmed to produce ratiometric measurements using reference capacitances to minimise parasitic effects. Finally, a USB interface undertakes the task of communicating the results to a personal computer. Characterization of the system was performed using (a) discrete capacitances and (b) capacitive pressure sensors. The system was evaluated in a capacitance range of 10---140 pF exhibiting high linearity (r = 0.9954) with sensitivity of 0.062 μs/pF when tested using in-house made capacitive pressure sensors.

A Wireless Sensor Readout System—Circuit Concept, Simulation, and Accuracy

In this paper, we present an electronic readout system for wireless passive sensors based on inductively coupled LC resonant circuits. The proposed system consists of a reader coil inductively coupled to the sensor circuit, an analog frontend circuit, and a digital signal processing unit. The analog frontend circuit generates a dc voltage representing the sensor resonance curve. The frequency of the reader coil driving signal is continuously readjusted by the digital signal processing unit. Based on analytical calculation and system simulation, we derive a model for the achievable accuracy of the overall sensor and readout system. The accuracy is limited by noise and systematic errors due to the measurement principle. We show how to design the digital signal processing system for optimal insensitivity to voltage noise. The noise sensitivity of the measurement system is inversely proportional to the square of the quality factor of the LC sensor. This means that minimizing the losses of the sensor is of crucial importance to obtain a wireless measurement system with a high range and a good insensitivity to noise. Subsequently, we outline an approach to calculate the sensor resonance frequency, quality factor, and inductive coupling factor from the available voltage signals in the signal processing unit using linear fitting functions. The accuracy of our approach is exemplified by a system simulation for typical sensor parameters. For the system studied, we show that the relative linearization error of the sensor resonance frequency measurement is below 0.02%. Taking the general models presented for both the noise sensitivity and linearization error into account, it is possible to estimate the maximum distance and accuracy for any wireless sensor system based on an inductively coupled LC resonator.

FPGA-based readout for double-sided silicon strip detectors

This work presents an FPGA-based readout system for double-sided silicon strip sensors based on the APV25 front-end chip. The system consists of an ADC-card and a digital readout board containing an FPGA. Data extraction algorithms implemented in the FPGA allow baseline and pedestal correction, hit detection and event-building. These algorithms represent an efficient data reduction tool and provide high readout rates.Details of the system, the algorithms applied and performance will be discussed featuring data collected in various tests experiments.

A Portable Readout System for Microstrip Silicon Sensors (ALIBAVA)

A readout system for microstrip silicon sensors has been developed. This system is able to measure the collected charge in one or two microstrip silicon sensors by reading out all the channels of the sensor(s), up to 256. The system can operate either with non-irradiated and irradiated sensors as well as with n-type and p-type microstrip silicon sensors. Heavily irradiated sensors will be used at the Super Large Hadron Collider, so this system can be used to research the performance of microstrip silicon sensors in conditions as similar as possible to the Super Large Hadron Collider operating conditions. The system has two main parts: a hardware part and a software part. The hardware part acquires the sensor signals either from external trigger inputs, in case of a radioactive source setup is used, or from a synchronised trigger output generated by the system, if a laser setup is used. The software controls the system and processes the data acquired from the sensors in order to store it in an adequate format. The main characteristics of the system will be described. Results of measurements acquired with n-type and p-type non-irradiated detectors using both the laser and the radioactive source setup will be also presented and discussed.

Sensor development and readout prototyping for the STAR Pixel detector

The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) is designing a new vertex detector. The purpose of this upgrade detector is to provide high resolution pointing to allow for the direct topological reconstruction of heavy flavor decays such as the D0 by finding vertices displaced from the collision vertex by greater than 60 microns. We are using Monolithic Active Pixel Sensor (MAPS) as the sensor technology and have a coupled sensor development and readout system plan that leads to a final detector with a <200 μs integration time, 400 M pixels and a coverage of -1 < η < 1. We present our coupled sensor and readout development plan and the status of the prototyping work that has been accomplished.

Improved Performance of the Preamplifier-Shaper Design for a High-Density Sensor Readout System

Improved Performance of the Preamplifier-Shaper Design for a High-Density Sensor Readout System

Results from a prototype MAPS sensor telescope and readout system with zero suppression for the heavy flavor tracker at STAR

We describe a three Mimostar-2 Monolithic Active Pixel Sensor (MAPS) sensor telescope prototype with an accompanying readout system incorporating on-the-fly data sparsification. The system has been characterized and we report on the measured performance of the sensor telescope and readout system in beam tests conducted both at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL) and in the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). This effort is part of the development and prototyping work that will lead to a vertex detector for the STAR experiment.

Universal Readout System for Temperature, Elongation and Hydrostatic Pressure Sensors Based on Highly Birefringent Fibers

In this paper, we present a universal readout system, which can be used to decode polarimetric fiber-optic sensors based on highly birefringent fibers. All such sensors use the same sensing principle, relying upon the dependence of modal birefringence on different physical parameters. To register the measurand-induced phase changes between polarization modes, we use the coherence-addressing principle. This requires that the interrogated sensor be powered by a broadband source (superluminescent diode) and that the total optical path delay introduced by the sensor be balanced in the decoding interferometer. The system performance in decoding elongation, temperature and hydrostatic pressure sensing is demonstrated.

Feasibility study of online high-spatial-resolution MOSFET dosimetry in static and pulsed x-ray radiation fields

Improvements have been made in the measurement of dose profiles in several types of X-ray beams. These include 120-kVp X-ray beams from an orthovoltage X-ray machine, 6-MV Bremsstrahlung from a medical LINAC in conformal mode and the 50-200 keV energy spectrum of microbeams produced at the medical beamline station of the European Synchrotron Radiation Facility. Using a quadruple metal-oxide-semiconductor field-effect transistor (MOSFET) sensor chip in "edge on" mode together with a newly developed sensor readout system, the feasibility of online scanning of the profiles of quasi-static and pulsed radiation beams was demonstrated. Measurements of synchrotron pulsed microbeams showed that a micrometer-scale spatial resolution was achievable. The use of several MOSFETs on the same chip gave rise to the correction of misalignments of the oxide films of the sensor with respect to the microbeam, ensuring that the excellent spatial resolution of the MOSFET used in "edge-on" mode was fully utilized.