Lecture 3: Diodes And Transistors - MIT OpenCourseWare
2.996/6.971 Biomedical Devices DesignLaboratoryLecture 3: Diodes andTransistorsInstructor: Hong MaSept. 17, 2007
Diode Behavior Forward bias– Exponential behavior Reverse biasI– Breakdown– Controlled breakdown Æ ZenersVZ Zener knee voltage-VZCompressedscale0VBreakdown0.7 V VV tI (V ) I S e 1 Vt kTQV
Types of Diode Silicon diode (0.7V turn-on)Schottky diode (0.3V turn-on)LED (Light-Emitting Diode) (0.7-5V)PhotodiodeZenerTransient Voltage Suppressor
Silicon Diode 0.7V turn-on Important specs:– Maximum forward current– Reverse leakage current– Reverse breakdownvoltage Typical parts:Part #IF, maxIRVR, maxCost1N914200mA25nA at 20V100 0.0075µA at 50V50V 0.021N4001 1A
Schottky Diode Metal-semiconductor junction 0.3V turn-onOften used in power applicationsFast switching – no reverse recovery timeLimitation: reverse leakage current is higher– New SiC Schottky diodes have lower reverse leakage
Reverse Recovery Time Test Jig
Reverse Recovery Test Results Device tested: 2N4004 diode
Light Emitting Diode (LED) Turn-on voltage from 0.7V to 5V 5 years ago: blue and white LEDsRecently: high power LEDs for lightingNeed to limit current
LEDs in Parallel VV I (V ) I S e t 1 RVS 3.3VRVS 3.3VRR IS is stronglydependent on temp. Resistance decreaseswith increasingtemperature “Power Hogging”
Photodiode Photons generate electron-hole pairs Apply reverse bias voltage to increase sensitivity Key specifications:––––Sensitivity (short-circuit current for a given light level)Spectral responseReverse breakdown voltageDark currentRVBIASPDLOAD
IZenersVZ Zener knee voltage-VZCompressedscale0VBreakdown Utilize reverse breakdown mechanismSharper transition than forward biased diodeKnee Voltages range from 1.8V to 200V to kVReverse leakage current is higherApplications– Limiter– Voltage reference0.7 VV
Transient Voltage Suppressor TVS or TransOrbPlace in parallel with power supplyAbsorbs over-voltageUnipolar or bipolarTypical specs:––––Absorb 1000W for 1msBreakdown voltage (VBR)Standoff voltage ( 0.9VBR)Vsupply Vstandoff
Diode Application:Preventing Inductive Kickback From Maxwell’s equations:dIV Ldt Instantaneous current switchingproduces very large voltages!ISinSin
Voltage References With forward biased diode With Zener Temperature compensated reference – bandgap reference
Peak Detector AKA: Envelop detector
RectifierHalf-waveFull-wave
Diode Clamper Zener has bad leakage Don’t forget about failure mode
Diode Tx-Rx Switch Mylar balloon used both as a speaker and a microphone D3 and D4 limit the voltage at the input of U2
Transistors(as switches)
BJT Three-terminal device: base, emitter, collector Two types: NPN and PNP IC βIB, β 100Typical parts: 2N3904 (NPN), 2N3906 (PNP)
BJT as a Switch Need a resistor to limit base current Many IC’s leave RL unconnected – open collector output Emitter follower: output tracks input with 0.7V offsetCommon-EmitterEmitter follower
Problems with BJTs Negative temperature coefficient Parallel BJTs: Power hogging Large BJTs: secondary breakdown
MOSFETDrainDrainBodyGateGateSourceSourceN-channel MOSFETSourceSourceGateGateBodyDrainP-channel MOSFET Four-terminal device: gate, source, drain, and bodyN-type and P-typeNegative temperature coefficient Æ can be parallelizedBidirectional - so long as body-drain diode remain reverse biasedDrain
MOSFET as SwitchesVSVSImportant Specs Gate capacitance (CG)– Hundreds of pFRLOAD On resistance (RDS(on))VIN– RDS N-ch RDS P-chVINRLOAD– Use N-channel wheneverpossible Threshold voltage (VTH)– As low as 1.8VLow-side SwitchHigh-side Switch Drain-source breakdownvoltage (VDSS)
Gate Drivers Efficiency dependent on transition time Low-side driver – low impedance drive High-side driver – charge pump to create gate voltageabove the source voltage
H-BridgesKey Issue Shoot throughcurrentLMD18200 High, low gatedrivers Current sensing Current limiting ThermalshutdownReprinted with permission of the National Semiconductor Corporation.
CMOS Analog SwitchesSignal inVSControlKey Issues for Analog Circuits Signal range Switch on-resistance Resistance matchingSignal out
Logic Gates
Logic Family Conversion 10VTTLHCTACTHCACTTLOKOKAOKOKABHCT, ACTOKOKOKNOOKOKBHC, ACOKOKOKNOOKOKBHC, AC @3.3VOKOKNOOKOKBBNMOS, LSIOKOKAOKOKAB4000B, 74C@5VOKaOKOKNOOKOKB4000B, 74C@10VCCCCCCOK(a) with limited fanout.A - pullup to 5V, or use HCT as interface.B - use i)OC pullup to 10V, or ii)40109, 14504, or LTC1045 level translator.C - use 74C901/2, 4049/50, 14504, or LTC1045 level translator.
Metal-semiconductor junction 0.3V turn-on Often used in power applications Fast switching – no reverse recovery time Limitation: reverse leakage current is higher – New SiC Schottky diodes have lower reverse leakage
direction typically include one or more diodes in the circuit design. Today the most common diodes are made from semiconductor materials such as silicon or germanium. There are a variety of diodes; A few important ones are described below. Normal (p-n) diodes The operation of these diodes is the subject of this document. Usually made of
Introduction of Chemical Reaction Engineering Introduction about Chemical Engineering 0:31:15 0:31:09. Lecture 14 Lecture 15 Lecture 16 Lecture 17 Lecture 18 Lecture 19 Lecture 20 Lecture 21 Lecture 22 Lecture 23 Lecture 24 Lecture 25 Lecture 26 Lecture 27 Lecture 28 Lecture
SEMICONDUCTORS 2.PDF 1 E. COATES 2016 Semiconductor Diodes Module 2.0 Diodes Introduction Diodes are one of the simplest, but most useful of all semiconductor devices. Many types of diode are used for a wide range of applications. Rectifier diodes are a vital component in power supplies wher
SPICE for the Complete Idiot C. H. Ting Silicon Valley FIG 4/30/2005. TRANSISTORS AND DIODES Junction Diodes Diode Model (D) Bipolar Junction Transistors (BJTs) BJT Models (NPN/PNP) Junction Field-Effect Transistors (JFETs) JFET Models . D Diode model NPN NPN BJT model
gate JL transistors, multi-gate JL transistors, silicon on insulator (SOI) JL transistors, and gate all around JL transistors. . For the SHE in FinFETs, various methods and the structures of transistors able to reduce this effect were considered in many works [11-15]. In [11], the charge plasma (CP) based JL MOSFET on a selective buried .
Lecture 1: A Beginner's Guide Lecture 2: Introduction to Programming Lecture 3: Introduction to C, structure of C programming Lecture 4: Elements of C Lecture 5: Variables, Statements, Expressions Lecture 6: Input-Output in C Lecture 7: Formatted Input-Output Lecture 8: Operators Lecture 9: Operators continued
We invite you to review our complete catalog of packaged and unpackaged semiconductor diodes, passive elements, and switches for speci c RF and microwave applications. Products include silicon varactors, PIN diodes, Schottky diodes, GaAs Schottky diodes, passive elements, and PHEMT-based . is testing performed on a sample of the lot to .
3 A product Line of Diodes Incorporated PI5A100 www.diodes.com December 2017 Diodes Incorporated PI5A100 Document Number DS40515 Rev 1-2 Notes: 1. The algebraic convention, where the most negative value is a minimum and the most positive is a maximum, is used in this data sheet.
