Editorial

2 pages, 154 KiB

Open AccessEditorial

Editorial for the Special Issue on Interface Circuits for Microsensor Integrated Systems

by Giuseppe Ferri and Vincenzo Stornelli

Micromachines 2018, 9(10), 527; https://doi.org/10.3390/mi9100527 - 17 Oct 2018

Viewed by 1948

Recent advances in sensing technologies, especially those for Microsensor Integrated Systems, have led to several new commercial applications. [...] Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

Research

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13 pages, 4294 KiB

Open AccessArticle

A Novel Electronic Interface for Micromachined Si-Based Photomultipliers

by Leonardo Pantoli, Gianluca Barile, Alfiero Leoni, Mirco Muttillo and Vincenzo Stornelli

Micromachines 2018, 9(10), 507; https://doi.org/10.3390/mi9100507 - 08 Oct 2018

Cited by 23 | Viewed by 2879

Abstract

In this manuscript, the authors propose a novel interface for silicon photomultipliers based on a second-generation voltage conveyor as an active element, performing as a transimpedance amplifier. Due to the absence of internal feedback, this solution offers a static bandwidth regardless of the [...] Read more.

In this manuscript, the authors propose a novel interface for silicon photomultipliers based on a second-generation voltage conveyor as an active element, performing as a transimpedance amplifier. Due to the absence of internal feedback, this solution offers a static bandwidth regardless of the tunable gain level. The simulation results have shown good performances, confirming the possibility of the proposed interface being effectively used in different scenarios. A preliminary hybrid solution has also been developed using second-generation current conveyors and measurements conducted on an equivalent discrete-elements board, which is promising. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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21 pages, 2167 KiB

Open AccessArticle

On Frequency-Based Interface Circuits for Capacitive MEMS Accelerometers

by Zhiliang Qiao, Boris A. Boom, Anne-Johan Annema, Remco J. Wiegerink and Bram Nauta

Micromachines 2018, 9(10), 488; https://doi.org/10.3390/mi9100488 - 25 Sep 2018

Cited by 7 | Viewed by 4307

Abstract

Interface circuits for capacitive MEMS accelerometers are conventionally based on charge-based approaches. A promising alternative to these is provided by frequency-based readout techniques that have some unique advantages as well as a few challenges associated with them. This paper addresses these techniques and [...] Read more.

Interface circuits for capacitive MEMS accelerometers are conventionally based on charge-based approaches. A promising alternative to these is provided by frequency-based readout techniques that have some unique advantages as well as a few challenges associated with them. This paper addresses these techniques and presents a derivation of the fundamental resolution limits that are imposed on them by phase noise. Starting with an overview of basic operating principles, associated properties and challenges, the discussions then focus on the fundamental trade-offs between noise, power dissipation and signal bandwidth (BW) for the LC-oscillator-based frequency readout and for the conventional charge-based switched-capacitor (SC) readout. Closed-form analytical formulas are derived to facilitate a fair comparison between the two approaches. Benchmarking results indicate that, with the same bandwidth requirement, charge-based readout circuits are more suitable when optimizing for noise performance, while there is still some room for frequency-based techniques when optimizing for power consumption, especially when flicker phase noise can be mitigated. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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22 pages, 4826 KiB

Open AccessArticle

Interrogation Techniques and Interface Circuits for Coil-Coupled Passive Sensors

by Marco Demori, Marco Baù, Marco Ferrari and Vittorio Ferrari

Micromachines 2018, 9(9), 449; https://doi.org/10.3390/mi9090449 - 09 Sep 2018

Cited by 26 | Viewed by 4827

Abstract

Coil-coupled passive sensors can be interrogated without contact, exploiting the magnetic coupling between two coils forming a telemetric proximity link. A primary coil connected to the interface circuit forms the readout unit, while a passive sensor connected to a secondary coil forms the [...] Read more.

Coil-coupled passive sensors can be interrogated without contact, exploiting the magnetic coupling between two coils forming a telemetric proximity link. A primary coil connected to the interface circuit forms the readout unit, while a passive sensor connected to a secondary coil forms the sensor unit. This work is focused on the interrogation of sensor units based on resonance, denoted as resonant sensor units, in which the readout signals are the resonant frequency and, possibly, the quality factor. Specifically, capacitive and electromechanical piezoelectric resonator sensor units are considered. Two interrogation techniques, namely a frequency-domain technique and a time-domain technique, have been analyzed, that are theoretically independent of the coupling between the coils which, in turn, ensure that the sensor readings are not affected by the interrogation distance. However, it is shown that the unavoidable parasitic capacitance in parallel to the readout coil introduces, for both techniques, an undesired dependence of the readings on the interrogation distance. This effect is especially marked for capacitance sensor units. A compensation circuit is innovatively proposed to counteract the effects of the parasitic input capacitance, and advantageously obtain distance-independent readings in real operating conditions. Experimental tests on a coil-coupled capacitance sensor with resonance at 5.45 MHz have shown a deviation within 1.5 kHz, i.e., 300 ppm, for interrogation distances of up to 18 mm. For the same distance range, with a coil-coupled quartz crystal resonator with a mechanical resonant frequency of 4.432 MHz, variations of less than 1.8 Hz, i.e., 0.5 ppm, have been obtained. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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16 pages, 10236 KiB

Open AccessArticle

Reconfigurable Sensor Analog Front-End Using Low-Noise Chopper-Stabilized Delta-Sigma Capacitance-to-Digital Converter

by Hyungseup Kim, Byeoncheol Lee, Yeongjin Mun, Jaesung Kim, Kwonsang Han, Youngtaek Roh, Dongkyu Song, Seounghoon Huh and Hyoungho Ko

Micromachines 2018, 9(7), 347; https://doi.org/10.3390/mi9070347 - 10 Jul 2018

Cited by 8 | Viewed by 5249

Abstract

This paper proposes a reconfigurable sensor analog front-end using low-noise chopper-stabilized delta-sigma capacitance-to-digital converter (CDC) for capacitive microsensors. The proposed reconfigurable sensor analog front-end can drive both capacitive microsensors and voltage signals by direct conversion without a front-end amplifier. The reconfigurable scheme of [...] Read more.

This paper proposes a reconfigurable sensor analog front-end using low-noise chopper-stabilized delta-sigma capacitance-to-digital converter (CDC) for capacitive microsensors. The proposed reconfigurable sensor analog front-end can drive both capacitive microsensors and voltage signals by direct conversion without a front-end amplifier. The reconfigurable scheme of the front-end can be implemented in various multi-mode applications, where it is equipped with a fully integrated temperature sensor. A chopper stabilization technique is implemented here to achieve a low-noise characteristic by reducing unexpected low-frequency noises such as offsets and flicker noise. The prototype chip of the proposed sensor analog front-end is fabricated by a standard 0.18-μm 1-poly-6-metal (1P6M) complementary metal-oxide-semiconductor (CMOS) process. It occupies a total active area of 5.37 mm² and achieves an effective resolution of 16.3-bit. The total power consumption is 0.843 mW with a 1.8 V power supply. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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12 pages, 11891 KiB

Open AccessArticle

Resonant Directly Coupled Inductors–Capacitors Ladder Network Shows a New, Interesting Property Useful for Application in the Sensor Field, Down to Micrometric Dimensions

by Arnaldo D’Amico, Marco Santonico, Giorgio Pennazza, Alessandro Zompanti, Emma Scipioni, Giuseppe Ferri, Vincenzo Stornelli, Marcello Salmeri and Roberto Lojacono

Micromachines 2018, 9(7), 343; https://doi.org/10.3390/mi9070343 - 07 Jul 2018

Cited by 3 | Viewed by 3244

Abstract

The study of ladder networks made by sequences of directly coupled inductor–capacitor single cells has led us to discover a new property, which may be of certain interest in the sensor field. In the case of n cells, the n-frequencies vector characterizing each [...] Read more.

The study of ladder networks made by sequences of directly coupled inductor–capacitor single cells has led us to discover a new property, which may be of certain interest in the sensor field. In the case of n cells, the n-frequencies vector characterizing each node may allow for the identification of that capacitor (sensor), which has experienced a variation of its nominal value. This localization is possible independently from the observable node of the ladder network as proven by the application of the following multivariate data analysis techniques: principal component analysis and partial least square discriminant analysis. This property can be applied on a large scale down to micrometric dimensions in agreement with the technologic ability to shrink the capacitive sensor dimensions. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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20 pages, 4340 KiB

Open AccessArticle

The Evolution of Integrated Interfaces for MEMS Microphones

by Piero Malcovati and Andrea Baschirotto

Micromachines 2018, 9(7), 323; https://doi.org/10.3390/mi9070323 - 26 Jun 2018

Cited by 22 | Viewed by 6646

Abstract

Over the last decade, MEMS microphones have become the leading solution for implementing the audio module in most portable devices. One of the main drivers for the success of the MEMS microphone has been the continuous improvement of the corresponding integrated interface circuit [...] Read more.

Over the last decade, MEMS microphones have become the leading solution for implementing the audio module in most portable devices. One of the main drivers for the success of the MEMS microphone has been the continuous improvement of the corresponding integrated interface circuit performance in terms of both dynamic range and power consumption, which enabled the introduction in mobile devices of additional functionalities, such as Hi-Fi audio recording or voice commands. As a result, MEMS microphone interface circuits evolved from just simple amplification stages to complex mixed-signal circuits, including A/D converters, with ever improving performance. This paper provides an overview of such evolution based on actual design examples, focusing, finally, on the latest cutting-edge solutions. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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13 pages, 7526 KiB

Open AccessArticle

Chopper-Stabilized Instrumentation Amplifier with Automatic Frequency Tuning Loop

by Chen-Mao Wu, Hsiao-Chin Chen, Ming-Yu Yen and San-Ching Yang

Micromachines 2018, 9(6), 289; https://doi.org/10.3390/mi9060289 - 08 Jun 2018

Cited by 5 | Viewed by 5129

Abstract

A variable-gain chopper-stabilized instrumentation amplifier (chopper IA), which employs a low pass filter (LPF) to attenuate the up-converted noise at the chopping frequency, is presented. The circuit is designed and fabricated with Taiwan Semiconductor Manufacturing Company (TSMC) (Hsinchu, Taiwan) 0.18 μm complementary metal-oxide-semiconductor [...] Read more.

A variable-gain chopper-stabilized instrumentation amplifier (chopper IA), which employs a low pass filter (LPF) to attenuate the up-converted noise at the chopping frequency, is presented. The circuit is designed and fabricated with Taiwan Semiconductor Manufacturing Company (TSMC) (Hsinchu, Taiwan) 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology. Consuming 1.1 mW from a 1.2 V supply voltage, the chopper IA achieves a variable gain of 20.7–48.5 dB, with a minimum bandwidth of 6.7 kHz and a common-mode rejection ratio (CMRR) of 95 dB below 10 kHz. By using the chopper technique, the input-referred noise of the chopper IA can be reduced to 0.28 μVrms (0~96 kHz), with a chopping frequency of 83.3 kHz. An automatic frequency tuning loop (ATL) is employed to adjust the corner frequency of the LPF dynamically so that the frequency ratio between the chopping frequency and the LPF corner frequency is 8.3, ensuring a noise reduction of 36.7 dB. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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10 pages, 4100 KiB

Open AccessArticle

A Low Power Energy-Efficient Precision CMOS Temperature Sensor ^†

by Rongshan Wei and Xiaotian Bao

Micromachines 2018, 9(6), 257; https://doi.org/10.3390/mi9060257 - 24 May 2018

Cited by 7 | Viewed by 3688

Abstract

This paper presents a low power, energy-efficient precision CMOS temperature sensor. The front-end circuit is based on bipolar junction transistors, and employs a pre-bias circuit and bipolar core. To reduce measurement errors arising from current ratio mismatch, a new dynamic element-matching mode is [...] Read more.

This paper presents a low power, energy-efficient precision CMOS temperature sensor. The front-end circuit is based on bipolar junction transistors, and employs a pre-bias circuit and bipolar core. To reduce measurement errors arising from current ratio mismatch, a new dynamic element-matching mode is proposed, which dynamically matches all current sources in the front-end circuit. The first-order fitting and third-order fitting are used to calibrate the output results. On the basis of simulation results, the sensor achieves 3σ-inaccuracies of +0.18/−0.13 °C from −55 °C to +125 °C. Measurement results demonstrate sensor 3σ-inaccuracies of ±0.2 °C from 0 °C to +100 °C. The circuit is implemented in 0.18 μm CMOS, and consumes 6.1 μA with a 1.8 V supply voltage. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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8 pages, 5807 KiB

Open AccessArticle

An Adaptable Interface Conditioning Circuit Based on Triboelectric Nanogenerators for Self-Powered Sensors

by Yongshan Hu, Qiuqin Yue, Shan Lu, Dongchen Yang, Shuxin Shi, Xiaokun Zhang and Hua Yu

Micromachines 2018, 9(3), 105; https://doi.org/10.3390/mi9030105 - 01 Mar 2018

Cited by 9 | Viewed by 5179

Abstract

In order to solve the limited life problem of typical battery power supply, a self-powered method that is based on the environmental energy harvesting has emerged as an amazing power supply approach. The Tribo-electric-Nano-generator (TENG) has been widely studied because of its high [...] Read more.

In order to solve the limited life problem of typical battery power supply, a self-powered method that is based on the environmental energy harvesting has emerged as an amazing power supply approach. The Tribo-electric-Nano-generator (TENG) has been widely studied because of its high efficiency, low fabrication cost, and high output voltage. However, low output power conversion efficiency has restricted its practical application because of its own extremely high output impedance. In order to match the high output impedance of TENG and increase the output power, this paper presents an adaptable interface conditioning circuit, which is composed of an impedance matching circuit, a synchronous rectifier bridge, a control circuit, and an energy storage device. In the impedance matching circuit, the energy loss of coupling inductance could be reduced by using the bi-directional switch to increase the frequency, and impedance matching circuit can be used to increase the output efficiency of TENG. Experimental results show that, in about 3.6 s, the storing capacitor voltage was basically stable at 5.5 V by using the proposed adapted interface conditioning circuit in this paper. The charging efficiency has increased by 50%. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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Review

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17 pages, 3200 KiB

Open AccessReview

Recent Progress in Rapid Sintering of Nanosilver for Electronics Applications

by Wei Liu, Rong An, Chunqing Wang, Zhen Zheng, Yanhong Tian, Ronglin Xu and Zhongtao Wang

Micromachines 2018, 9(7), 346; https://doi.org/10.3390/mi9070346 - 10 Jul 2018

Cited by 42 | Viewed by 5590

Abstract

Recently, nanosilver pastes have emerged as one of the most promising high temperature bonding materials for high frequency and high power applications, which provide an effective lead-free electronic packaging solution instead of high-lead and gold-based solders. Although nanosilver pastes can be sintered at [...] Read more.

Recently, nanosilver pastes have emerged as one of the most promising high temperature bonding materials for high frequency and high power applications, which provide an effective lead-free electronic packaging solution instead of high-lead and gold-based solders. Although nanosilver pastes can be sintered at lower temperature compared to bulk silver, applications of nanosilver pastes are limited by long-term sintering time (20–30 min), relative high sintering temperature (>250 °C), and applied external pressure, which may damage chips and electronic components. Therefore, low temperature rapid sintering processes that can obtain excellent nanosilver joints are anticipated. In this regard, we present a review of recent progress in the rapid sintering of nanosilver pastes. Preparation of nanosilver particles and pastes, mechanisms of nanopastes sintering, and different rapid sintering processes are discussed. Emphasis is placed on the properties of sintered joints obtained by different sintering processes such as electric current assisted sintering, spark plasma sintering, and laser sintering, etc. Although the research on rapid sintering processes for nanosilver pastes has made a great breakthrough over the past few decades, investigations on mechanisms of rapid sintering, and the performance of joints fabricated by pastes with different compositions and morphologies are still far from enough. Full article

(This article belongs to the Special Issue Interface Circuits for Microsensor Integrated Systems)

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