scholarly journals Reducing Measurement Time in Direct Interface Circuits for Resistive Sensor Readout

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2596
Author(s):  
José A. Hidalgo-López ◽  
José A. Sánchez-Durán ◽  
Óscar Oballe-Peinado
Keyword(s):  
Estimation Method ◽  
Calibration Method ◽  
Digital Conversion ◽  
Digital Device ◽  
Interface Circuits ◽  
Analog To Digital ◽  
Slowing Down ◽  
Resistive Sensor ◽  
Relative Errors ◽  
Capacitor Charge

Direct Interface Circuits (DICs) carry out resistive sensor readings using a resistance-to-time-to-digital conversion without the need for analog-to-digital converters. The main advantage of this approach is the simplicity involved in designing a DIC, which only requires some additional resistors and a capacitor in order to perform the conversion. The main drawback is the time needed for this conversion, which is given by the sum of up to three capacitor charge times and their associated discharge times. This article presents a modification of the most widely used estimation method in a resistive DIC, which is known as the Two-Point Calibration Method (TPCM), in which a single additional programmable digital device pin in the DIC and one extra measurement in each discharge cycle, made without slowing down the cycle, allow charge times to be reduced more than 20-fold to values around 2 µs. The new method designed to achieve this reduction only penalizes relative errors with a small increase of between 0.2% and 0.3% for most values in the tested resistance range.

scholarly journals Two-Capacitor Direct Interface Circuit for Resistive Sensor Measurements

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1524
Author(s):  
José A. Hidalgo-López ◽  
Óscar Oballe-Peinado ◽  
Julián Castellanos-Ramos ◽  
José A. Sánchez-Durán
Keyword(s):  
Digital Device ◽  
Interface Circuits ◽  
Capacitor Discharge ◽  
Interface Circuit ◽  
Analog To Digital ◽  
Resistive Sensor ◽  
High Measurement ◽  
Field Programmable ◽  
Small Resistance ◽  
Digital Measurements

Direct interface circuits (DICs) avoid the need for signal conditioning circuits and analog-to-digital converters (ADCs) to obtain digital measurements of resistive sensors using only a few passive elements. However, such simple hardware can lead to quantization errors when measuring small resistance values as well as high measurement times and uncertainties for high resistances. Different solutions to some of these problems have been presented in the literature over recent years, although the increased uncertainty in measurements at higher resistance values is a problem that has remained unaddressed. This article presents an economical hardware solution that only requires an extra capacitor to reduce this problem. The circuit is implemented with a field-programmable gate array (FPGA) as a programmable digital device. The new proposal significantly reduces the uncertainty in the time measurements. As a result, the high resistance errors decreased by up to 90%. The circuit requires three capacitor discharge cycles, as is needed in a classic DIC. Therefore, the time to estimate resistance increases slightly, between 2.7% and 4.6%.

scholarly journals Fast Calibration Methods for Resistive Sensor Readout Based on Direct Interface Circuits

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3871 ◽  
Author(s):  
Hidalgo-López ◽  
Botín-Córdoba ◽  
Sánchez-Durán ◽  
Oballe-Peinado
Keyword(s):  
Digital Information ◽  
Discharge Time ◽  
Digital Device ◽  
Interface Circuits ◽  
Simple Method ◽  
Interface Circuit ◽  
Calibration Methods ◽  
Resistive Sensor ◽  
Field Programmable ◽  
Conversion Time

A simple method to measure the resistance of a sensor and convert it into digital information in a programmable digital device is by using a direct interface circuit. This type of circuit deduces the value of the resistor based on the discharge time through it for a capacitor of a known value. Moreover, the discharge times of this capacitor should be measured through one or two resistors with known values in order to ensure that the estimate is not dependent on certain parameters that change with time, temperature, or aging. This can slow down the conversion speed, especially for high resistance values. To overcome this problem, we propose a modified process in which part of the discharge, which was previously performed through the resistive sensor only, is only conducted with the smallest calibration resistor. Two variants of this operation method, which differ in the reduction of the total time necessary for evaluation and in the uncertainty of the measurements, are presented. Experiments carried out with a field programmable gate array (FPGA); using these methodologies achieved reductions in the resistance conversion time of up to 55%. These reductions may imply an increase in the uncertainty of the measurements; however, the tests carried out show that with a suitable choice of parameters, the increases in uncertainty, and therefore errors, may be negligible compared to the direct interface circuits described in the literature.

scholarly journals Quasi Single Point Calibration Method for High-Speed Measurements of Resistive Sensors

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 664 ◽  
Author(s):  
Botín-Córdoba ◽  
Oballe-Peinado ◽  
Sánchez-Durán ◽  
Hidalgo-López
Keyword(s):  
High Speed ◽  
Single Point ◽  
Calibration Method ◽  
Digital Conversion ◽  
Interface Circuits ◽  
Sensor Reading ◽  
Mean Estimation ◽  
Calibration Methods ◽  
Proposal A ◽  
The Mean

Direct interface circuits are a simple, inexpensive alternative for the digital conversion of a sensor reading, and in some of these circuits only passive calibration elements are required in order to carry out this conversion. In the case of resistive sensors, the most accurate methods of calibration, namely two-point calibration method (TPCM) and fast calibration methods I and II (FCMs I and II), require two calibration resistors to estimate the value of a sensor. However, although FCMs I and II considerably reduce the time necessary to estimate the value of the sensor, this may still be excessive in certain applications, such as when making repetitive readings of a sensor or readings of a large series of sensors. For these situations, this paper proposes a series of calibration methods that decrease the mean estimation time. Some of the proposed methods are based on the TPCM and quasi single-point calibration methods, while others make the most of the advantages of FCM II and fast quasi single-point calibration methods. In general, the proposed methods significantly reduce estimation times in exchange for a small increase in errors. To validate the proposal, a circuit with a Xilinx XC3S50AN-4TQG144C FPGA has been designed and resistors in the range (267.56 Ω, 7464.5 Ω) have been measured. For 20 repetitive measurements, the proposed methods achieve time reductions of up to 61% with a relative error increase of only 0.1%.

Energy Harvesting via Analog-to-Digital Conversion

2021 ◽  
Author(s):  
Neha Jain ◽  
Nir Shlezinger ◽  
Yonina C. Eldar ◽  
Anubha Gupta ◽  
Vivek Ashok Bohara
Keyword(s):  
Energy Harvesting ◽  
Digital Conversion ◽  
Analog To Digital ◽  
Analog To Digital Conversion

Design of a 20-Gsps 12-bit time-interleaved analog-to-digital conversion system

2021 ◽  
Vol 32 (3) ◽  
Author(s):  
Ruo-Shi Dong ◽  
Lei Zhao ◽  
Jia-Jun Qin ◽  
Wen-Tao Zhong ◽  
Yi-Chun Fan ◽  
...  
Keyword(s):  
Digital Conversion ◽  
Analog To Digital ◽  
Analog To Digital Conversion ◽  
Conversion System ◽  
Time Interleaved

scholarly journals How to Control Errors in Analog-To-Digital Conversion

1993 ◽  
Vol 7 (4) ◽  
pp. 408 ◽  
Author(s):  
James R. Matey ◽  
M.J. Lauterbach
Keyword(s):  
Digital Conversion ◽  
Analog To Digital ◽  
Analog To Digital Conversion

1550 nm mode-locked semiconductor lasers for all-optical analog-to-digital conversion

2017 ◽  
Author(s):  
Evgenii S. Kolodeznyi ◽  
Innokenty I. Novikov ◽  
Andrey V. Babichev ◽  
Alexander S. Kurochkin ◽  
Andrey G. Gladyshev ◽  
...  
Keyword(s):  
Semiconductor Lasers ◽  
Digital Conversion ◽  
Analog To Digital ◽  
Analog To Digital Conversion ◽  
All Optical ◽  
Optical Analog

scholarly journals Photonic analog-to-digital conversion based on time-to-frequency mapping

2021 ◽  
pp. 127440
Author(s):  
Hao Chi ◽  
Qiulin Zhang ◽  
Shuna Yang ◽  
Bo Yang ◽  
Yanrong Zhai ◽  
...  
Keyword(s):  
Digital Conversion ◽  
Analog To Digital ◽  
Analog To Digital Conversion
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