Electronic Components and Material Properties

Q3)B ● High pass filter ○ ○ ○ Capacitor behavior Resistor network Frequency dependence Operational Amplifier ● High-gain electronic voltage amplifier with differential inputs ○ ● single output Used to amplify weak electrical signals Features ● High input impedance ○ ● Low output impedance ○ ● Prevents loading of the input signal Can drive loads effectively High Gain ○ ○ High open loop gain 10^5 to 10^6 Basic Operation of an Op-Amp ● Ideal characteristics ○ ○ ○ Infinite input impedance (Zin=∞) Zero output impedance (Zout=0) Infinite open loop gain (AOL=∞) Common Op-Amplifier ● Inverting Amplifier ○ ○ ● Non-Inverting Amplifier ○ ○ ● Output is 180° out of phase with the input. Gain: Output is in phase with the input. Gain: Buffer(Voltage Follower) ○ ○ Provides unity gain(Av=1) Used to isolate stages without loading the signal. Bode plot of Op-AMP ● May look similar to Low-Pass ○ ○ Open loop gain Band width Similar plot does not mean it has same mechanism 2022 Midterm Q5) a ● ● R2=10kΩ Target frequencies ○ ○ ● w1=200rad/s w2=20krad/s Max gain: AM=26dB Therefore, our gain would be around 20 Q5) a ● ● Calculate Resistance using Gain A Given that A=20 and R2=10kΩ Q5) a ● C1 ○ ○ ● R1=500Ω w1=200rad/s C2 ○ ○ R2=10,000Ω w2=20,000rad/s Q5) a Conclusion ● ● ● ● R1=500Ω R2=10kΩ C1=10𝝻F C2=5nF Q5)b 1. Plot the gain response a. b. ● ● X-axis i. Frequency w Y-axis i. Gain ∣H(jω)∣ Gain AM=26dB Corner freq ○ ○ w1=200rad/s w2=20krad/s Q5) c 1. Plot phase response a. b. ● ● ● X-axis: Frequency Y-axis: Phrase arg(H(jw)) in degree At low frequency, phase≈ 0° Near w1, phase shift begins At high frequency(w2): phase≈-180° Q5)d 1. Input characteristics a. 2. Input waveform Vin i. Type: Triangular wave ii. Amplitude 2V iii. Frequency 2krad/s Consider Output limitation a. Op-amp has a maximum output of 土10V Conduction ● Conductors ○ ● Insulators ○ ● Materials with free electrons in the conduction band Materials with a large energy gap between the valence and conduction bands Semiconductors ○ Materials with a small controllable energy gap allowing conduction under certain conditions Band theory ● Conductors ○ ● Insulator ○ ● Partially filled conduction band or overlapping valence and conduction bands Large Band gap(>5eV) Semiconductor ○ Bandgap typically between 0.5~2eV Mechanisms of Electrical conduction in Metal ● Drude Model ○ ● Quantum Model ○ ● ● Electrons obeys Fermi-Dirac statistics Ohm’s Law Resistivity(p) ○ ● Electron behaves like gas of charged particles Temperature, impurities, defects sensitive -(Matthiessen’s rule) Scattering mechanisms ○ ○ ○ Phonon scattering Impurity scattering Electron-electron scattering Electrical Conduction-Semiconductors ● ● Electrical conduction in semiconductors depends on intrinsic carriers Doping ○ ○ ● n-type(donor electron) p-type(acceptor) Carrier concentration varies with temperature ○ Intrinsic carrier concentration Electrical Conduction-Semiconductors ● ● Fermi level Mobility ○ ● Affected byy scattering processes Applications ○ Transistors, diodes, solar cells Why Insulators Don’t Conduct? ● Large bandgap on insulators ○ ● prevent electron excitation Electron mobility minimal Thermal Conduction in Solids ● Thermal conduction is mediated by ○ ○ Electrons-in metals Photons- in non-metals ● Fourier’s Heat Conduction ● Wiedemann-Franz Law Conductors – Quantum Model of Conduction ● Fermi surface ○ ○ ● Mean free path ○ ● Defines the disruption of electrons at absolute zero At non-zero, electrons near the Fermi surface participate in conduction Distance an electron travels before scatters Thermal conductivity ○ Metal dominated by electron transport and is proportional to temperature Phonon-Mediated Thermal Conduction in Insulators ● Photon scattering ○ ● Debye model ○ ● Increases with temperature, limits heat conduction Describes heat capacity and phonon behavior in solid Thermal Resistance ○ Lattice defects, grain boundaries and photon scattering Semiconductors: Thermal and Electrical Conduction ● ● Both electrical and thermal conduction Thermoelectric effect ○ Convert thea gradient into electrical voltage Factors Affecting Conductivity in Solids ● ● ● ● Temperature Impurities and Defects Crystal structures External fields PN-Junction ● Boundary between two semiconductor material ○ ● Between p and n type Formation of the junction of p-type and n-type material ○ Diffusion of charge carriers across the junction Energy Band Diagram of a PN-Junction ● Before Junction formation ○ ● Distinct energy levels for P-types and N-types After Junction formation ○ ○ Formation of depletion region Creation of built in potential barrier Forward Biasing the PN-Junction ● Forward Bias ○ ○ ● Effects on Forward voltage ○ ○ ● P-type connected to positive terminal N-type connected to negative terminal Reduces potential barrier Allows charge carriers to move freely Current flow ○ ○ Device enters ON state Increased current flow through junction Reverse Biasing the PN-Junction ● Reverse Bias ○ ○ ● Effects of Reverse Voltage ○ ○ ● P-type connected to negative terminal N-type connected to positive terminal Increases potential barrier Widening of depletion region Current Behavior ○ ○ Minimal current flow Device remains in OFF state Difference between Forward and Reverse bias ● Forward bias ○ ○ Exterior potential given at terminals of P/N Decrease the area of potentials that permits movement of current ● Reverse bias ○ ○ Exterior voltage given to Pn junction of diode for increasing the area of potential barrier Stops the movement of current Application of PN junctions ● Diodes ○ ● Transistors ○ ● Allow currents to flow in only one direction Serves as amplifiers and switches Solar Cells ○ Converts sunlight into electrical energy