F4250 Aplikace elektroniky poznámky úvod diody • Dioda a tranzistor, jejich vlastnosti a měření. LED diody • Nízkofrekvenční zesilovače. • Operační zesilovač, základní zapojení, využití. • Zdroje referenčního napětí • Analogová a digitální informace. AD a DA převodník. • Analogový a digitální záznam a přenos zvuku a obrazu. Druhy modulace. Rozhlasový vysílač a přijímač. • Speciální elektronické součástky • Elektronická zařízení v domácnostech a automobilech. Měřicí přístroje Brief introduction to semiconductors T=0 All electrons are bound in valence bond T >0 Thermal fluctuations excite electrons from valence bonds. Electron hole pairs are created • Insulator: Large band gap. Difficult for electron to jumto conduction band • Semiconductor: Thermal excitations at room temperature. Moderate applied voltage can bridge gap • Conductors: conduction and valence bands overlap. Charges flows freely Conduction band Valence band Forbidden energy gap (band gap) Thermal activated electron hole pair Intrinsic semiconductors: No impurities Dopped semiconductors As electron donor 5 valence electrons B electron acceptor 3 valence electron Conduction band Valence band Conduction band Valence band holes electrons donors acceptorsBand gap P-N junction N type P type electrons holes Band gap Charges diffuse due to thermal effect Holes diffuse from right side to left side Electron diffuse from left side to right side P-N junction N type P type electrons holes Band gap Charges diffuse due to thermal effect Holes diffuse from right side to left side Electron diffuse from left side to right side + Fixed space charge Electrics field N type P type electrons holes Band gap + N type P type electrons holes Band gap + Fermi energy Electric fiel U N type P type electrons holes + + - P-N junction +- electrons holes Band gap + No total curreent recombinatio • Voltampérová charakteristika diody • Křemík Eg=1,2 eV • Germánium Eg=0,7 eV )1(  kT eU eJJ s kT E s g eeBTJ   3 )1(0  kT eU eII This model is most often used to expain the operation of rectifiers Rectifiers are AC to DC conversion circuit U U threshold is 0.6 V for silicon diodes simple diode model diode Diode maintenance • Standard diode safety precautions • Avoid • current overloads • excessively high operating voltages • high temperature Testing s diode • using an ohmmeter • a dynamic diode tester. Rectification Half wave bridge Full wave bridge Other types of diodes • Voltage regulation diode (Zener diode) • Light emitting diode • Variable capacitance diode Zener diode (voltage regulation diode) • Silicon diodes up to about 5.6 volts, the tunelling effect is the predominant • temperature coefficient is negative. • Above 5.6 volts, the avalanche effect becomes predominant • temperature coefficient is positive • 5.6 V diode, the two effects occur together • temperature coefficients is almost zero Precision reference Uref • Cirrus logic. VRE204 • range 4.5 V accuracy +/- 0.4 mV • temperature coefficient 0.6 ppm/C, • -55+125 C • stability 6 ppm/1000h • line regulation 6ppm/V • Supply range13,5-22,0 V • based on 6.3 zener diode Light emitting diode LED • lineární zářivky, např. Lumilux 36 W produkují 3350 lm což je 93 lm/W • vysoce výkonné LED diody CREE dosahují až 90 lm/W • metalhalogenidová výbojka Narva 70W produkuje 5500 lm tedy 78,6 lm/W • xenonová výbojka do automobilu cca. 70-90 lm/W (Osram uvádí 3050 lm u 35W výbojky) • vysokoteplotní žárovka až 35 lm/w • halogenová žárovka 20 lm/W (Osram uvádí 18 lm/W u automobilových halogenových žárovek) • osram LED Dragon 2W poskytuje asi 40 lm, což je 20 lm/W [1] • laboratorně dosažený světelný tok u high power LED CREE byl v roce 2007 v hodnotách 130 lm/W • bílá výkonná LED využívající vhodný luminofor běžně dosahuje 30 lm/W • jednotlivá bílá 5mm LED poskytuje 1,8 lm, což je cca. 18-25 lm/W • trubicová halogenová žárovka 13-14 lm/W • klasická žárovka 60 W na 230V vykazuje světelný tok 12 lm/W Více zde: http://www.podzemi.net/news/porovnavani-svetelnych-zdroju/ • Color Wavelength range (nm) Typical efficiency (lm/W) • Red 620 < λ < 645 72 • Red-orange 610 < λ < 620 98 • Green 520 < λ < 550 93 • Cyan 490 < λ < 520 75 • Blue 460 < λ < 490 37 • Truncated 5800 K blackbody[note 2] 251[7] 37% • Green light at 555 nm (maximum possible luminous efficacy)683 lm/W • compact fluorecent 46-75 lm/W • color voltage drop • infrared 1,6 V • red 1,8 V až 2,1 V • orange 2,2 V • yellow 2,4 V • green 2,6 V • blue 3,0 V až 3,5 V • white 3,0 V až 3,5 V • Ultraviolet 3,5 V varicap varactor U C 1 Kapacity 10-1000 pF Ur [V] C [pF] 20 20 - - - - - - - - - - + + + + + ++ ++ + + + + - + - - d +- nejvhodnější průběh Tuner AFC diode 1S2638 Tunell diode Esaki 1958 • Ph.D. research student Esaki in 1958 • structure • very high doping levels • depletion region 5-10 nm Tunnel diode Shottky diode • Advantages • Voltage drop in forvard direction is relativelly low (0 at 1 mA is in the range 0.15 V to 0.46 V, see the 1N5817, 1N5711) • The reverse recovery time is relativelly short (up to 0.1 ns small signal diodes) / Si p-n diode up 100 ns Shotky diode • Disadvantages (silicon-metal) contrary (carbide silicon-metal) • Relatively high leakage current (hundreds of nA) • low reverse voltage (approx. 50 V up 200 V)/CSi-M up (1700 V) • Thermal instability / Csi-M up to 200 C • Low surge resistance Schottky diode • Small-signal Schottky diodes 1N5711,1N6263, 1SS106, 1SS108, 41– 43, 45–49 Gunn diode transferred electron device (TED) • 1963 John Battiscombe Gunn • osciace pro intenzitu řádově několik 1000 V/cm • microwave oscilator Gunn diode, operation principle • elektron velocity in GaAs • 3.2 kV/cm low mobility valley • in Gunn domain up to 50 kV/cm • velocity of domain cca 105 m/s Gallium arsenide Gunn diodes frequencies up to 200 GHz gallium nitride materials can reach up to 3 terahertz. Transil – Leakage current. – Maximum reverse standoff voltage – Breakdown voltage – Clamping voltage: the voltage at which the device will conduct its fully rated current (hundreds to thousands of amperes). – Parasitic capacitance – Parasitic inductance – Amount of energy it can absorb Transil-trisil (A),(B),(C) transil (D),(E) trisil PIN diode • RF switches, attenuators, photodetectors. • RF switches -1us • photodetector • photovoltaic cell • capacitance 1 pF (at 320MHz reactance 500 Ω)