Advanced compact model and processing circuit for integrated magnetic sensor systems

The generalized electric model of the Hall sensor, which is designed for circuit simulation, is taken into account the features of its design and used for manufacturing materials. The model of the Hall sensor is implemented in the language Verilog-A, has a simple structure and allows to accurately describe its performance characteristics.

Kỹ thuật điện tử ADVANCED COMPACT MODEL AND PROCESSING CIRCUIT FOR INTEGRATED MAGNETIC SENSOR SYSTEMS Dao Dinh Ha1*, Tran Tuan Trung2 Abstract: The generalized electric model of the Hall sensor, which is designed for circuit simulation, is taken into account the features of its design and used for manufacturing materials The model of the Hall sensor is implemented in the language Verilog-A, has a simple structure and allows to accurately describe its performance characteristics The equivalent circuit of the sensor is built on the basis of standard subcomponents and does not use complex equations to describe the physical processes in its structure A circuit and topological solution consisting of Hall sensor, differential amplifier and 10-bit successive approximation register analog-to-digital converter and other components integrated on a single chip using the TSMC 0.18 μm CMOS MS/RF 1,8/3,3V PDK design library, allowing to receive and process data of sensor devices Keywords: Hall sensor; Compact Model; Verilog-A; Signal processing circuit; Analog-to-digital converter INTRODUCTION In modern electronics sensors for measuring the induction of a magnetic field, contactless determination of mechanical and electrical influences is widely used This type of sensor is used in the automotive, mobile and consumer segments, medicine, aerospace and marine industries, power engineering – as sensors for cameras and displays, electronic compasses, etc [1] For practical applications, the Hall sensor (HS) is usually placed with a signal processing circuit on a single chip However, the constructive implementation of such a system remains a problem, because the sensor models are not included in the design library provided by the chip manufacturer Standard models for describing the electrical characteristics of HS are too complex [2] or idealized [3] 2D or 3D physical models described by FEM simulators for integration with circuit simulation programs require significant computational costs [3], but are useful for analyzing the effect of geometric parameters on the behavior of a sensor To improve design efficiency and system performance, it is necessary to have an electrical (SPICE) model that adequately describes the characteristics of the sensor element Such a model describes the behavior of the sensor using a set of equations obtained by means of adequate assumptions and simplifications Another important task in the field of sensor design is the development of systems that provide accurate processing of input data, as well as their conversion to a digital signal The latter would greatly simplify the process of further analysis of the results of measurements These tasks can be solved by sharing amplifiers and analog-to-digital converters, which enable the transition to a digital representation of the original analog signal with small amplitude The paper presents the results of the development of a unified compact model of a Hall sensor fabricated both by standard silicon technology and based on widegap semiconductors The model also provides the ability to account for the material and geometry of the integrated magnetic concentrator (IMC) designed to increase the sensitivity of the sensor A circuit-based solution consisting of a low196 D D Ha, T T Trung, “Advanced compact model … integrated magnetic sensor systems.” Nghiên cứu khoa học công nghệ noise amplifier and an analog-to-digital converter, which allows receiving and processing of sensor data, is developed and topologically realized SIMULATION TOOLS, INVESTIGATED SENSOR CONSTRUCTIONS AND COMPACT MODEL DESCRIPTION 2.1 Investigated Hall Sensor designs In the calculations presented below, the simulation of the electric characteristics of the Hall sensor was carried out in the Silvaco software environment [4], the IMC parameters were calculated in the FEMM program [5], the Verilog-A [6] language was used to develop the electrical model, and the compact model and circuit solutions were designed and tested using Cadence software [7] Fig shows the HS designs that are being investigated The design presented on the left is a sensor manufactured using standard silicon technology [8], the design on the right is a sensor based on gallium nitride [9] W L L W contact contact oxide n+ Ti/Al/Ni/Au n+ t n-well AlxGa1-xN GaN depletion layer AlN Sapphire (0001) p-substrate Figure Investigated Hall Sensors designs D θ l d Figure Modeling determining the parameters of material sample by CST Tạp chí Nghiên cứu KH&CN quân sự, Số Đặc san Viện Điện tử, - 2020 197 Kỹ thuật điện tử Fig shows the sensor system design, which includes an IMC It consists of four HS (2) and an IMC (3) formed on a silicon substrate (1) Four HS are perpendicular to each other along the edges of the IMC Between the IMC and the HS there is a dielectric layer (4) of thickness d The IMC is a disk of a ferromagnetic material with a diameter D, a thickness l, and a deflection angle θ Supermindur which has a high induction of magnetic saturation was used as the IMC material Earlier studies were carried out to optimize the design and technology, electrical and operational characteristics of presented sensors types within the device-technological simulation [8-10, 12] 2.2 Advanced compact model of the Hall Sensor Fig shows an equivalent circuit describing the HS compact For an ideal design (no technological discrepancy and mechanical stress in the system), the van der Pauw method is used to measure the surface resistance of the RS layer Since the device is symmetrical, it is necessary to determine the values of the two resistances between the contacts: RD for the resistance between the two opposite and RH for the two adjacent contacts [11] In comparison with the existing solutions [12], this scheme provides the possibility of taking into account the galvanomagnetic and temperature effects INPUT + RH RD RD CCVS4 + - OUTPUT RH RD + - CCVS2 CCVS1 RH RD OUTPUT RH B CCVS3 + R INPUT Figure Equivalent circuit describing the basic HS compact model The proposed equivalent circuit has electrical outputs and one external source as input (B) and includes the following components: non-linear resistors designed to describe the dependences of the characteristics of the HS from the magnetic field and temperature; current-controlled voltage sources, which allow estimating the contributions to the Hall voltage of currents flowing through nonlinear resistances; interface blocks for the simulation of series resistances The parameters of the silicon-based HS compact model [11] are given in Table 198 D D Ha, T T Trung, “Advanced compact model … integrated magnetic sensor systems.” Nghiên cứu khoa học công nghệ The last two lines contain the parameters typical for the hall sensor made on the basis of wide-gap semiconductors The names of electrical model parameters used in the text are shown in parentheses To simulate the magnetosensitive sensor with IMC, added the parameters presented in Table Table Silicon based hall sensor model parameters Parameter Description Unit Value range TEMP Ambient temperature K 248–398 L Length of active area m (30–120)×10-6 W Active Area Width m (10–40)×10-6 S (s) Size of the contact electrode M (9–39)×10-6 TETA (θ) Hall angle radians 0–0.45 RH (rH) The Hall Scattering Coefficient 0.2–1.7 GH (GH) Correction geometric coefficient 0,5–1 Concentration of charge carriers in -3 NDNW (ND,NW) m 1021–1023 the active region Concentration of charge carriers in a NSUB (NSUB) m-3 5×1020–1021 substrate DEFF (deff) Effective depth of active area m (0.55)ì10-6 Mobility of electrons in the active MOBN (àn) m2/V∙s 0.072–0.141 region Mobility of holes in the active MOBH (µh) m2/V∙s 0.032–0.047 region RSS (RS) Surface resistance of silicon Ohm 100–15×103 Resistance between two opposite RDD (RD) Ohm 650–120×103 contacts Resistance between two neighboring RHH (RH) Ohm 1100–200×103 opposites The first coefficient of resistance BBR1 V-1 0–0.01 versus voltage The second coefficient of resistance BBR2 V-2 -0.005–0 versus voltage The first coefficient of sensitivity BBS1 V-1 0–0.01 versus voltage The second coefficient of sensitivity BBS2 V-2 -0.005–0 versus voltage The first temperature coefficient of RTC1 V-1 0–0.01 resistance The second temperature coefficient RTC2 V-2 0–0.0005 of resistance Temperature coefficient of ALPHA (αSI) V-1 0–0.001 sensitivity Concentration of charge carriers in NSS (NS) m-2 1016–1018 2DEG MOBN (µS) Mobility of electrons in 2DEG m2/V∙s 0.01–1.0 Tạp chí Nghiên cứu KH&CN quân sự, Số Đặc san Viện Điện tử, - 2020 199 Kỹ thuật điện tử Table The compact model parameters of the magnetosensitive sensor with IMC Parameter Description Unit Value range D Diameter of the concentrator m (50–500)×10-6 t Thickness of concentrator m (520)ì10-6 Mu0 (à0) Magnetic permeability (1–100)×103 BSAT (Bsat) Magnetic saturation induction Tesla 1–2.8 N Demagnetization factor 0.015–0.15 K Coefficient of magnetic flux 5–20 SIMULATION RESULTS 3.1 Device-technological vs Schematic simulation Fig and show the results of a comparison between data of devicetechnological modeling in the software complex Silvaco and data of circuit simulation using the developed compact model a Hall sensor fabricated by standard silicon technology and based on wide-gap semiconductors, respectively Device simulation 150 B = 0.5 T B = 0.25 T B = 0.1 T 125 Compact Model VH , mV 100 B = 0.5 T B = 0.25 T B = 0.1 T 75 50 25 0 0,2 0,4 0,6 I , mA 0,8 1,0 Figure The simulated and modeled output Hall voltage VH versus the biasing current at different magnetic field for Silicon Hall sensor The analysis of the obtained results testifies to the high efficiency of the developed compact model The error in the data of device-technological and circuit simulation does not exceed 5% 40 35 30 VH , mV 25 20 Device simulation B = 0.5 T B = 0.25 T B = 0.1 T Compact Model B = 0.5 T B = 0.25 T B = 0.1 T 15 10 0,2 0,4 0,6 I , mA 0,8 1,0 Figure The simulated and modeled output Hall voltage VH versus the biasing current at different magnetic field for GaN Hall sensor 200 D D Ha, T T Trung, “Advanced compact model … integrated magnetic sensor systems.” Nghiên cứu khoa học công nghệ 3.2 Modeling of the sensor signal processing circuit Currently widely used multi-functional integrated sensor systems that are realized by combining the sensor (often multiple) and processing circuitry on a single chip Such a system-on-chip (SoC) in which the data converter is integrated with the digital signal processing unit in one chip with integrated sensor may be a more effective solution In comparison with optional discrete chip ADC, this approach can significantly improve the compactness and reduce the cost of production, which is a critical consideration for the sensitive region, medical, mobile, automotive, and other applications The processing of the sensor signal can be widely classified in terms of signal bandwidth (the rate of change of the measured physical quantity) and the resolution necessary to obtain meaningful information Typically, the required ADC can be built on the basis of one of two very efficient architectures: a sequential approximation register (SAR) and redundant discrete ADCs SigmaDelta (SD) Used in our case SAR ADC allows to effectively handle signals with a different frequency range – from a few Hz to hundreds of kHz with a high enough accuracy – 6-8 bits to 20 bits and higher, and also provides high versatility and low power dissipation, making it ideal for these systems Table 10-bit SAR ADC parameters Value Parameter name Designation Unit Min Typical Max Temperature T -40 27 85 °C Supply voltage of analog blocks VDDA 1.62 1.8 1.98 V Supply voltage of digital blocks VDDD 1.62 1.8 1.98 V Resolution N 10 bit Clock frequency FCLK 160 MHz Sampling rate FS 10 MHz Sampling time TS ns VREFP 1.25 V Reference voltages VREFN 0.25 V DC level of input signal VCM 0.75 V Input capacitance CIN pF Spurious free dynamic range SFDR 63 dB Signal to noise ratio and distortion SINAD 57 dB Effective number of bits ENOB 9.2 bits Integral nonlinearity INL LSB Differential nonlinearity DNL 0.7 LSB For this system, a topology which contains a system for receiving, amplifying, and sensory data processing based on the Hall sensor as an example on a single chip is developed using the TSMC 0.18 μm CMOS MS/RF 1.8/3.3V PDK The test circuit used a 10-bit, own designed SAR ADC implemented in silicon using TSMC 0.18 um CMOS MS/RF 1.8/3.3V technology The topological implementation of the Hall sensor, differential amplifier and ADC are presented in Fig Tạp chí Nghiên cứu KH&CN quân sự, Số Đặc san Viện Điện tử, - 2020 201 Kỹ thuật điện tử The results of computer simulation in the Cadence software package using the proposed signal processing circuit are presented in Fig and Table During the simulation, developed and described above compact model was used to simulate the HS electrical characteristics In Fig shows: B - magnetic field, VH+, VH- - hall voltage, code - DAC output signal, out - 10-bit ADC output signal 710 um – Hall sensor – Differential amplifier – Voltage reference – ADC 1168 um V V V V mV mT Figure Topological implementation of Hall sensor, differential amplifier and ADC В 500 770 750 730 1,5 0,8 VH+ refp 1,8 0,9 1,8 0,9 1,0 0,5 VHrefn vcm data code out 0,5 1,0 1,5 2,5 2,0 3,0 3,5 4,0 4,5 Time, us Figure The «Hall Sensor – processing circuit» system simulation results CONCLUSION The advanced compact model of Hall sensor presented in this paper has a simple structure which leads to fast simulations while allowing an accurate description of the behavior of the device It is made of simple sub-components and does not involve any complex equation The revision and expending of the model, primarily the mobility, provide the possibility of its use for simulation of Hall sensor based on other materials, for example wide-gap semiconductors and consider the impact of an integrated magnetic concentrator The results of simulation of the "Hall sensor – processing scheme" system using the developed compact model and signal processing circuit demonstrate the high efficiency of the proposed solutions 202 D D Ha, T T Trung, “Advanced compact model … integrated magnetic sensor systems.” Nghiên cứu khoa học công nghệ REFERENCES [1] R Popovic, "Hall Effect Devices" Institute of Physics Publising Second Edition 420 p (2004) [2] E Jovanovic, T Pesic and D Pantic, "3D simulation of cross-shaped Hall sensor and its equivalent circuit model" Proceedings of the 24th International Conference on Microelectronics, pp 235-238 (2004) [3] A Rossini, F Borghetti, P Malcovati, "Behavioral model of magnetic sensors for SPICE simulations", ICECS, pp 1-4 (2005) [4] https://www.silvaco.com [5] http://www.femm.info/wiki/HomePage [6] K Kundert, "The Designer's Guide to Verilog-AMS" Kluwert Academic Publishers, Boston (2004) [7] https://www.cadence.com [8] H Dao, A Belous, V Saladukha, "Optimization of structural and technological parameters of the field effect Hall sensor" ATC, Vietnam, pp 642–644 (2015) [9] V Stempitsky, Dao Dinh Ha, Tran Tuan Trung "Suppression of the SelfHeating Effect in AlGaN/GaN High Electron Mobility Transistor by Diamond Heat Sink Layers" ATC, Vietnam, pp 264–267 (2016) [10] Dao Dinh Ha, V Stempitsky, "Investigation of the Hall Sensor Characteristics with Various Geometry of the Active Area", Nano- i Mikrosistemnaya Tekhnika, vol.20, no.3, pp 174-186 (2018) [11] Y Xu and H Pan, "An Improved Equivalent Simulation Model for CMOS Integrated Hall Plates" Sensors, vol 11, pp 6284-6296 (2011) [12] Dao Dinh Ha, V Stempitsky, Tran Tuan Trung, "Verilog-A compact model of the silicon Hall element" ICDV Vietnam, pp 41-46 (2017) TĨM TẮT MƠ HÌNH TỔNG QT TIÊN TIẾN VÀ MẠCH XỬ LÝ TÍN HIỆU CHO HỆ THỐNG CẢM BIẾN TỪ TRƯỜNG TÍCH HỢP Đề xuất mơ hình điện tổng quát cảm biến Hall, thiết kế cho mơ mạch, có tính đến tham số thiết kế vật liệu sử dụng Mơ hình cảm biến triển khai theo ngơn ngữ Verilog-A có cấu trúc đơn giản cho phép mơ tả xác đặc tính cảm biến Mơ hình tương đương mô tả dựa thành phần mạch điện tiêu chuẩn khơng sử dụng phương trình phức tạp để mơ tả q trình vật lý diễn cấu trúc cảm biến Thiết kế cấu trúc mạch bao gồm cảm biến Hall, mạch khuếch đại mạch chuyển đổi tín hiệu tương tự-số 10 bit tích hợp chip sử dụng thư viện thiết kế TSMC 0.18 um CMOS MS/RF 1,8/3,3V PDK cho phép nhận xử lý tín hiệu thiết bị cảm biến Từ khóa: Cảm biến Hall, Mơ hình nhỏ gọn; Verilog-A; Mạch xử lý tín hiệu; Mạch chuyển đổi tương tự-số Received 20th April 2020 Revised 21th August 2020 Published 28th August 2020 Author affiliations: Le Quy Don Technical University; Academy of Military Science and Technology *Corresponding author: havixuly@gmail.com Tạp chí Nghiên cứu KH&CN quân sự, Số Đặc san Viện Điện tử, - 2020 203 ... simulated and modeled output Hall voltage VH versus the biasing current at different magnetic field for GaN Hall sensor 200 D D Ha, T T Trung, ? ?Advanced compact model … integrated magnetic sensor systems. ”... developed compact model and signal processing circuit demonstrate the high efficiency of the proposed solutions 202 D D Ha, T T Trung, ? ?Advanced compact model … integrated magnetic sensor systems. ”... 3.2 Modeling of the sensor signal processing circuit Currently widely used multi-functional integrated sensor systems that are realized by combining the sensor (often multiple) and processing circuitry