EE40_Fall08_Lecture31 - Slide 1 EE40 Fall 08 Connie...

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Unformatted text preview: Slide 1 EE40 Fall 08 Connie Chang-Hasnain EE40 Lecture 31-34 Connie Chang-Hasnain Nov. 12, 14, 17, 19 Reading: Chap. 10 and Supplementary Notes Chap 3 Slide 2 EE40 Fall 08 Connie Chang-Hasnain integrated circuit A Zener diode is designed to operate in the breakdown mode. Zener Diode I D (A) V D (V) reverse (leakage) current forward current breakdown voltage R V BD = 15V V BD + v s ( t ) t + v o ( t ) Example : Slide 3 EE40 Fall 08 Connie Chang-Hasnain Level Shift Circuit- V C1 + R 1 V OUT +- V IN +- C 1 V IN t V OUT t Once the capacitor is charged by the negative most voltage the rest of the signal is shifted up by that amount. Slide 4 EE40 Fall 08 Connie Chang-Hasnain Voltage Doubler Circuit + V C21- R 2 V OUT +- V IN +- C 2- V C1 + R 1 V OUT +- V IN +- C 1 Level Shift Peak Detect The final output is the peak to peak voltage of the input. Slide 5 EE40 Fall 08 Connie Chang-Hasnain Half-wave Rectifier Circuits Adding a capacitor: what does it do? V m sin ( t) R V C +- Slide 6 EE40 Fall 08 Connie Chang-Hasnain Half-Wave Rectifier Current charging up capacitor Slide 7 EE40 Fall 08 Connie Chang-Hasnain Week 12 OUTLINE Basic Semiconductor Materials n and p doping Bandgap Gausss Law Poisson Equation Depletion approximation Diode I-V characteristics Lasers and LEDs Solar Cells Reading Supplementary Notes Chap 3 Slide 8 EE40 Fall 08 Connie Chang-Hasnain Conductors, Insulators and Semiconductors Solids with free electrons that is electrons not directly involved in the inter-atomic bonding- are the familiar metals (Cu, Al, Fe, Au, etc). Solids with no free electrons are the familiar insulators (glass, quartz crystals, ceramics, etc.) Silicon is an insulator, but at higher temperatures some of the bonding electrons can get free and make it a little conducting hence the term semiconductor Pure silicon is a poor conductor (and a poor insulator). It has 4 valence electrons, all of which are needed to bond with nearest neighbors. No free electrons. Slide 9 EE40 Fall 08 Connie Chang-Hasnain The Periodic Table III IV V Slide 10 EE40 Fall 08 Connie Chang-Hasnain Unit Cell of Crystalline Silicon Si (1s 2 2s 2 2p 6 3s 2 3p 2 ) 22 3 3 8 3 1 1 8 6 4 # 8 8 2 5.00 10 (5.43 10 ) Atoms cm Volume a cm-- + + = = = Slide 11 EE40 Fall 08 Connie Chang-Hasnain Electronic Bonds in Silicon 2-D picture of perfect crystal of pure silicon; double line is a Si-Si bond with each line representing an electron Two electrons in each bond Si ion (charge +4 q) Actual structure is 3-dimensional tetrahedral- just like carbon bonding in organic and inorganic materials. Essentially no free electrons, and no conduction - insulator Slide 12 EE40 Fall 08 Connie Chang-Hasnain Bandgap Electrons are mobile in the conduction band, while holes are mobile in the lower energy valence band....
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This note was uploaded on 10/24/2009 for the course EE 40 taught by Professor Chang-hasnain during the Fall '07 term at University of California, Berkeley.

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EE40_Fall08_Lecture31 - Slide 1 EE40 Fall 08 Connie...

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