Design of CMOS capacitance to frequency converter for high-temperature MEMS sensors
19 Dec 2013-pp 1-4
TL;DR: A CMOS capacitance to frequency convertor for capacitive MEMS sensors working in high temperature environments and has excellent stability over wide temperature range, good accuracy and high sensing resolution.
Abstract: We present a CMOS capacitance to frequency convertor for capacitive MEMS sensors working in high temperature environments. Many MEMS sensors are needed to work at the extended military temperature range from -55 oC to 175oC and require a suitable readout circuitry to detect, process, and transmit the sensor measurement data. The proposed CMOS circuitry uses a current to frequency conversion circuit to convert the sensor capacitance output into a digital output modulated in frequency. Pulse width control is implemented on-chip to control the pulse width of the output digital signal. The circuitry is implemented using IBM 0.13μm CMOS technology. Simulation results show that the circuitry has excellent stability over wide temperature range, good accuracy and high sensing resolution. The novelty in this work lies in the fact that a digital output is achieved without using complex analog to digital converter (ADC).
Citations
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01 Jul 1971
TL;DR: In this paper, the fabrication of a silicon carbide (SiC) junction field effect transistor (J-FET) was shown to be feasible and a simplified building block amplifier was constructed and tested.
Abstract: : The fabrication of a silicon carbide (SiC) junction field effect transistor (J-FET) was shown practicable. Several amplifier designs were breadboarded with silicon devices to study the required parameters. A simplified building block amplifier was constructed and tested. (Author)
101 citations
TL;DR: Experimental measurements have shown good linearity and accuracy in the estimation of capacitances, having a baseline or reaching a value ranging in a wide interval, as well as in the evaluation of more reduced variations of resistances, ranging from kiloohms to megaohms, also when compared with other solutions presented in the literature.
Abstract: In this paper, a new configuration of operational amplifier -based square-wave oscillator is proposed. The circuit performs an impedance-to-period (Z–T) conversion that, instead of a voltage integration typically performed by other solutions presented in the literature, is based on a voltage differentiation. This solution is suitable as first analogue uncalibrated front-end for capacitive and resistive (e.g. relative humidity and gas) sensors, working also, in the case of capacitive devices, for wide variation ranges (up to six capacitive variation decades). Moreover, through the setting of passive components, its sensitivity can be easily regulated. Experimental measurements, conducted on a prototype printed circuit board, with sample passive components and using the commercial capacitive humidity sensor Honeywell HCH-1000, have shown good linearity and accuracy in the estimation of capacitances, having a baseline or reaching a value ranging in a wide interval [picofarads–microfarads], as well as, with a lower accuracy, in the evaluation of more reduced variations of resistances, ranging from kiloohms to megaohms, also when compared with other solutions presented in the literature.
20 citations
TL;DR: A new capacitance-to-digital converter (CDC) that gives a digital output proportional to the measurand kx, independent of its nominal capacitance, is reported in this paper.
Abstract: A new capacitance-to-digital converter (CDC) that gives a digital output proportional to the measurand $kx$ , independent of its nominal capacitance, is reported in this paper. Various CDCs are available in the market, but their output is a function of the nominal value $C_{0}$ of the sensor. Thus, a manual correction is required in the output, whenever a new capacitive sensor is interfaced to such CDCs. Moreover, the $C_{0}$ of the sensors is usually a large value compared with the change in capacitance due to $kx$ . Thus, in a typical CDC, a large percentage of the output counts/bits is used to measure and represent the $C_{0}$ leading to an underutilization of the hardware as far as the measurement of $kx$ is concerned. The proposed CDC uses a new automatic calibration (AC), employing a switched-capacitor (SC) circuit-based voltage source in a feedback topology, and provides an output independent of the $C_{0}$ of the sensor employed. The proposed CDC is based on an SC dual-slope technique and possesses the advantages of the dual-slope conversion method. The CDC circuit is designed such that the entire full scale can be used for representing the change in the $kx$ . In addition to this advantage, the AC helps to remove the dependence on the accuracy of the reference capacitor employed in the CDC. A detailed analysis of the effect of various sources of errors in the CDC has been conducted and presented in this paper. A prototype of the proposed CDC has been developed and tested. The results obtained show that the output of the CDC is not a function of the $C_{0}~(C_{0}$ varied from 60 pF to 1.46 nF) of the sensors interfaced.
15 citations
Cites background from "Design of CMOS capacitance to frequ..."
...The outputs from the capacitanceto-frequency [12], capacitance-to-time interval [13], and capacitance-to-pulsewidth modulated schemes [14] presented earlier are function of the C0 of the sensor....
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TL;DR: In this article, an incremental delta-sigma based capacitance-to-digital converter for lossy capacitive sensors is presented, which utilizes a reference signal which depends on the amplitude and frequency of the input excitation signal.
Abstract: This paper presents an incremental delta-sigma based capacitance-to-digital converter for lossy capacitive sensors. The proposed converter consists of a capacitance-to-voltage converter followed by a single-bit incremental delta-sigma converter. Unlike conventional incremental-delta sigma converter where a fixed reference voltage signal is utilized, the proposed converter utilizes a reference signal which depends on the amplitude and frequency of the input excitation signal. The generated reference signal for the incremental-delta sigma converter reduces the error in the capacitance measurement due to variation in the excitation signal frequency and amplitude. In addition, the proposed converter utilizes a frequency-independent quadrature phase shifter circuit for the generation of reference π/2 phase-shifted signal for the phase-sensitive detection operation. Moreover, a modified clock counting approach is utilized to measure the sensor capacitance accurately. A prototype of the proposed circuit is fabricated using commercial off-the-shelf components and tested. The experimental results demonstrate that the circuit is able to measure the sensor capacitor in the range from 20 pF to 163 pF. The worst-case error in sensor capacitance measurement was less than 0.2%. Furthermore, the proposed converter experimentally provides a signal-to-noise ratio of 56.66 dB.
8 citations
11 May 2015
TL;DR: A capacitance-to-digital converter (CDC) that gives a digital value proportional to the change in the capacitance of a sensor, independent of its nominal capacitance, is presented in this paper.
Abstract: A capacitance-to-digital converter (CDC) that gives a digital value proportional to the change in the capacitance of a sensor, independent of its nominal capacitance, is presented in this paper. The CDC presented is suitable for single element capacitive sensors. For most of the CDCs, available in the market, the output depends on the nominal value of the sensor. Thus, a manual intervention for appropriate correction in the output is required whenever a new sensor is connected to such CDCs. The proposed CDC uses a simple automatic calibration, employing a digitally controlled reference voltage in a feedback topology, and provides an output independent of the nominal value of the sensor employed. This automatic calibration also removes the dependence on the accuracy of the absolute value of reference capacitor, in the final output. The proposed CDC is based on a switched-capacitor dual-slope technique and possesses the advantages of the dual-slope conversion method. A prototype CDC has been developed and the test results are presented. The results obtained show that the output of the proposed converter is not a function of the nominal capacitance of the sensor for a wide range (50 pF to 1.15 nF). For this range, the worst error noted from the prototype CDC was less than 0.65 %.
6 citations
Cites background from "Design of CMOS capacitance to frequ..."
...The outputs from the capacitance-to-frequency [9], capacitance-to-time interval [10] and capacitance-to-pulse width modulated schemes [11] presented earlier are function of the C0 of the sensor....
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References
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Book•
01 Jan 1999
TL;DR: The analysis and design techniques of CMOS integrated circuits that practicing engineers need to master to succeed can be found in this article, where the authors describe the thought process behind each circuit topology, but also consider the rationale behind each modification.
Abstract: The CMOS technology area has quickly grown, calling for a new text--and here it is, covering the analysis and design of CMOS integrated circuits that practicing engineers need to master to succeed. Filled with many examples and chapter-ending problems, the book not only describes the thought process behind each circuit topology, but also considers the rationale behind each modification. The analysis and design techniques focus on CMOS circuits but also apply to other IC technologies.
Table of contents
1 Introduction to Analog Design
2 Basic MOS Device Physics
3 Single-Stage Amplifiers
4 Differential Amplifiers
5 Passive and Active Current Mirrors
6 Frequency Response of Amplifiers
7 Noise
8 Feedback
9 Operational Amplifiers
10 Stability and Frequency Compensation
11 Bandgap References
12 Introduction to Switched-Capacitor Circuits
13 Nonlinearity and Mismatch
14 Oscillators
15 Phase-Locked Loops
16 Short-Channel Effects and Device Models
17 CMOS Processing Technology
18 Layout and Packaging
4,826 citations
Book•
01 Jan 1987
TL;DR: In this article, the authors present a simple MOS LARGE-SIGNAL MODEL (SPICE Level 1) and a small-signal model for the MOS TRANSISTOR.
Abstract: 1.1 ANALOG INTEGRATED CIRCUIT DESIGN 1.2 NOTATION, SYMBOLOGY AND TERMINOLOGY 1.3 ANALOG SIGNAL PROCESSING 1.4 EXAMPLE OF ANALOG VLSI MIXED-SIGNAL CIRCUIT DESIGN 2.1 BASIC MOS SEMICONDUCTOR FABRICATION PROCESSES 2.2 THE PN JUNCTION 2.3 THE MOS TRANSISTOR 2.4 PASSIVE COMPONENTS 2.5 OTHER CONSIDERATIONS OF CMOS TECHNOLOGY 3.1 SIMPLE MOS LARGE-SIGNAL MODEL (SPICE LEVEL 1) 3.2 OTHER MOS LARGE-SIGNAL MODEL PARAMETERS 3.3 SMALL-SIGNAL MODEL FOR THE MOS TRANSISTOR 3.4 COMPUTER SIMULATION MODELS 3.5 SUBTHRESHOLD MOS MODEL 3.6 SPICE SIMULATION OF MOS CIRCUITS 4.1 MOS SWITCH 4.2 MOS DIODE/ACTIVE RESISTOR 4.3 CURRENT SINKS AND SOURCES 4.4 CURRENT MIRRORS 4.5 CURRENT AND VOLTAGE REFERENCES 4.6 BANDGAP REFERENCE 5.1 INVERTERS 5.2 DIFFERENTIAL AMPLIFIERS 5.3 CASCODE AMPLIFIERS 5.4* CURRENT AMPLIFIERS 5.5* OUTPUT AMPLIFIERS/BUFFERS 6.1 DESIGN OF CMOS OP AMPS 6.2 COMPENSATION OF OP AMP 6.3 DESIGN OF TWO-STAGE OP AMPS 6.4 POWER-SUPPLY REJECTION RATIO OF TWO-STAGE OP AMPS 6.5 CASCODE OP AMPS 6.6 SIMULATION AND MEASUREMENT OF OP AMPS 6.7 MACROMODELS FOR OP AMPS 7.1 BUFFERED OP AMPS 7.2 HIGH-SPEED/FREQUENCY OP AMPS 7.3 DIFFERENTIAL-OUTPUT OP AMPS 7.4 MICROPOWER OP AMPS 7.5 LOW NOISE OP AMPS 7.6 LOW VOLTAGE OP AMPS 8.1 CHARACTERIZATION OF A COMPARATOR 8.2 TWO-STAGE, OPEN-LOOP COMPARATOR DESIGN 8.3 OTHER OPEN-LOOP COMPARATORS 8.4 IMPROVING THE PERFORMANCE OF OPEN-LOOP COMPARATORS 8.5 DISCRETE-TIME COMPARATORS 8.6 HIGH-SPEED COMPARATORS APPENDIX A CIRCUIT ANALYSIS FOR ANALOG CIRCUIT DESIGN APPENDIX B INTEGRATED CIRCUIT LAYOUT APPENDIX C CMOS DEVICE CHARACTERIZATION APPENDIX D TIME AND FREQUENCY DOMAIN RELATIONSHIP FOR SECOND-ORDER SYSTEMS
2,741 citations
07 Nov 2002
TL;DR: It appears unlikely that wide bandgap semiconductor devices will find much use in low-power transistor applications until the ambient temperature exceeds approximately 300/spl deg/C, as commercially available silicon and silicon-on-insulator technologies are already satisfying requirements for digital and analog VLSI in this temperature range.
Abstract: The fact that wide bandgap semiconductors are capable of electronic functionality at much higher temperatures than silicon has partially fueled their development, particularly in the case of SiC. It appears unlikely that wide bandgap semiconductor devices will find much use in low-power transistor applications until the ambient temperature exceeds approximately 300/spl deg/C, as commercially available silicon and silicon-on-insulator technologies are already satisfying requirements for digital and analog VLSI in this temperature range. However practical operation of silicon power devices at ambient temperatures above 200/spl deg/C appears problematic, as self-heating at higher power levels results in high internal junction temperatures and leakages. Thus, most electronic subsystems that simultaneously require high-temperature and high-power operation will necessarily be realized using wide bandgap devices, once they become widely available. Technological challenges impeding the realization of beneficial wide bandgap high ambient temperature electronics, including material growth, contacts, and packaging, are briefly discussed.
863 citations
"Design of CMOS capacitance to frequ..." refers background in this paper
...Therefore, the electronic interfaces are remotely placed in a cooler region or they must be actively or passively cooled, which inevitably introduces parasitic noise and additional overhead in the form of longer wires and more connectors resulting in increased size, weight and system complexity [6-8]....
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TL;DR: The physical and chemical properties of wide bandgap semiconductors silicon carbide and diamond make these materials an ideal choice for device fabrication for applications in many different areas, e.g. light emitters, high temperature and high power electronics, high power microwave devices, micro-electromechanical system (MEMS) technology, and substrates as mentioned in this paper.
Abstract: The physical and chemical properties of wide bandgap semiconductors silicon carbide and diamond make these materials an ideal choice for device fabrication for applications in many different areas, e.g. light emitters, high temperature and high power electronics, high power microwave devices, micro-electromechanical system (MEMS) technology, and substrates. These semiconductors have been recognized for several decades as being suitable for these applications, but until recently the low material quality has not allowed the fabrication of high quality devices. Silicon carbide and diamond based electronics are at different stages of their development. An overview of the status of silicon carbide's and diamond's application for high temperature electronics is presented.
268 citations
"Design of CMOS capacitance to frequ..." refers background in this paper
...The definition of high temperature here generally refers to temperature beyond 125oC, which is the upper limit of the military specification [1-5]....
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Book•
01 Feb 1997TL;DR: High Temperature Electronics as discussed by the authors provides a broad overview of the materials selection, design, and thermal management of high temperature electronics, as well as the tradeoffs involved in materials selection and design.
Abstract: The development of electronics that can operate at high temperatures has been identified as a critical technology for the next century. Increasingly, engineers will be called upon to design avionics, automotive, and geophysical electronic systems requiring components and packaging reliable to 200 °C and beyond. Until now, however, they have had no single resource on high temperature electronics to assist them.Such a resource is critically needed, since the design and manufacture of electronic components have now made it possible to design electronic systems that will operate reliably above the traditional temperature limit of 125 °C. However, successful system development efforts hinge on a firm understanding of the fundamentals of semiconductor physics and device processing, materials selection, package design, and thermal management, together with a knowledge of the intended application environments.High Temperature Electronics brings together this essential information and presents it for the first time in a unified way. Packaging and device engineers and technologists will find this book required reading for its coverage of the techniques and tradeoffs involved in materials selection, design, and thermal management and for its presentation of best design practices using actual fielded systems as examples. In addition, professors and students will find this book suitable for graduate-level courses because of its detailed level of explanation and its coverage of fundamental scientific concepts.Experts from the field of high temperature electronics have contributed to nine chapters covering topics ranging from semiconductor device selection to testing and final assembly.
176 citations