* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Integrated Magnetodiode Carrier
Edward Sabine wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Friction-plate electromagnetic couplings wikipedia , lookup
Electromagnetism wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Superconducting magnet wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Magnetic monopole wikipedia , lookup
Electromotive force wikipedia , lookup
Magnetic nanoparticles wikipedia , lookup
Induction heater wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Electromagnetic field wikipedia , lookup
Magnetometer wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Lorentz force wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Force between magnets wikipedia , lookup
Electromagnet wikipedia , lookup
Magnetoreception wikipedia , lookup
Magnetotellurics wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetochemistry wikipedia , lookup
Magnetic Sensors • by Kuen-Hsien Wu Galvano-magnetic effect: 1. 2. 3. Lorentz deflection – Lorentz force on charge carrier carrier deflection Magneto-resistance – Modulation of resistance by a magnetic field Magneto-concentration – Producing a gradient of carrier concentration perpendicular to the magnetic inductor vector and original current direction Magnetic Sensors and Effects Main Magnetic Sensors 1. 2. Hall Plates Integrated Hall Sensors 1) 2) 3. 4. 5. 6. Hall devices MAGFET Magneto-transistor Magneto-diode Carrier-domain Magnetometer Super Magneto-resistor Hall Plate Geometric Effects • VH = -GIBrn(qnt)-1 • rn: scattering factor • Geometric correction factor G – Describe the shapes effect of the plate • G depends on – – – – – Plate length Plate width Contact size Position of the sensor contact Hall angle H Biasing and Amplification Circuitry • Hall-voltage operation is preferred in mordern Hall devices. – Biased with a constant current source. • The left sensor contact is virtually grounded by an operational ampliier (OA) – The full Hall voltage appears at the right sensor contact. – Without the OA, a large common-mode voltage will appear at the amplifier input. Sensitivity • Absolute sensitivity – SA • Supply-current related sensitivity – SI • Supply-voltage related sensitivity – SV Limiting Effects • Noise • Offset Voltage • Temperature Coefficient • Nonlinearity Integrated Bulk Hall Sensor Integrated Hall Switch • A binary output signal is produced. Vertical Hall Device Equipotential line Differential Amplification Magnetic Sensor (DAMS) • • • With a Magnetic induction, the Hall voltage appears across the base region. If the two emitters are kept at the same potential, the Hall voltage acts as the differential emitterbase voltage of the transistor pair. Under proper bias conditions, this results in a corresponding collector-current difference, which can be converted into a final voltage difference by load resistors. Base Region Magnetic Field-Effect Transistor (MAGFET) • The surface inversion layer or channel of a MOSFET can be used as the active region of a Hall sensor. • This device exploits the Hall effect and the Lorentz deflection of carriers in the inversion layer. • Such a device is compatible with MOS bias and signal-conditioning circuitry. • Disadvantages: – High 1/f noise – Low channel mobility Magnetic Heterojunction Device (2DEG) – Surface instability Hall MAGFET Dual-Drain MAGFET • A magnetic induction perpendicular to the inversion layer produces a current imbalance. ID = ID1 – ID2 • ID=Gnch*(L/W)B ID Split-Drain MOSFET Magnetic Heterojunction Device 2DEG Magnetotransistor (MT) • Lorentz deflection – Lorentz force deflects minority carriers toward one collector and away from the other collector. • Injection modulation – The magnetic induction acting on the majority carriers moving in the base region creates a Hall voltage, which modulates the emitter-base voltage – Creating an asymmetry in the minority-carrier injection. • MT’s – Vertical Magnetotransistor – Lateral Magnetotransistor – Suppressed-Sidewall-Injection MT (SSIMT) Vertical Magnetotransistor • The Lorentz deflects the injected carriers in the base and the subsequent epi-layer causing a collector-current imbalance IC = IC1 – IC2 • IC=Gnch*(L/WE)B ICO Lateral Magnetotransistor (sensitive to perpendicular field) • The two n+ base contacts are used to create an accelerating field across the large base region. (different from the vertical MT) • Due to the accelerating voltage, most minority carriers injected from the emitter are directed towards the two collectors and only a small amount flows into the substrate. Large Base Region Lateral Magnetotransistor (sensitive to parallel field) • The device has only one collector and uses the substrate as a second collector. • The minority carriers flowing laterally through the base region are deflected either towards the collector or the substrate. • Thus, the ratio IC/IS is modulated by the magnetic field. Suppressed-Sidewall-Injection MT (SSIMT) • • • • IC = IC1 – IC2 B The highly-doped n+ guard ring surrounding the emitter prevents the lateral injection of minority carriers from the emitter into the base. – Improving the sensitivity An accelerating field is formed between the guard and the base contacts to boost the magnetic response. The substrate current deflection also cooperate the IC formation B Magnetodiode (MD) Integrated Magnetodiode Carrier-Domain Magnetometer (CDM) • Carrier Domain – A region of high, nonequilibrium carrier density. • A CDM – exploiting the action of Lorentz force on the charge carriers moving in the domain. – This force moves the entire carrier domain through the semiconductor or modulates a domain migration caused by some other effect. – Detection the domain motion provides information on the magnetic field. Vertical Four-Layer CDM • A perpendicular magnetic field produces a displacement of the domain, thus resulting in the current imbalance in Ip1 andIp1 (or In1 andIn1). • The current imbalance indicates the domain displacement, and hence the presence of the magnetic field. Carrier domain Circular, Horizontal Four-Layer CDM • Under the action of the magnetic induction, the domain travels around the circumference of the structure. • The frequency of this rotation is proportional to the applied magnetic induction. • This generation of a frequency output is a unique feature of thr circular CDM. • Disadvantage: – High threshold field – Large temperature coefficient Circular, Horizontal Three-Layer CDM • • • • No threshold magnetic induction is required. Operated in the collector-emitter breakdown regime with shortcircuited emitter and base contacts. The angular frequency of the carrier domain rotation is modulated by the magnetic field. Disadvantages: – High current (need cooling) – Breakdown voltage is not precise. short-circuited emitter and base contacts Supermagnetoresistor • • The sensor operates at the temperature of 77K and responses to very small fields (below 10 mT) A week magnetic field will disturb the superconductivity of a superconductor material. – This leads to an abrupt change in the resistance of the sample with magnetic field.