EE100Su08 Lecture 14 July 28th 2008 Outline MultiSim licenses trying to get new licenses HW 2 regrade deadline Monday 07 28 5 00 pm PST Midterm 1 regrades DONE QUESTIONS Bode plots Diodes Introduction Reading Appendix E skip second order resonance bode plots Chapter 1 from your reader skip second order resonance bode plots Chapter 2 from your reader Diode Circuits EE100 Summer 2008 Slide 1 Bharathwaj Muthuswamy Example Circuit R2 VIN R1 VT AVT C VOUT TransferFunction VIN VOUT AZ c VIN Z R Zc VOUT A 100 R1 100 000 Ohms R2 1000 Ohms C 10 uF VOUT A 1 jwC A VIN R2 1 j C 1 j R2C EE100 Summer 2008 Slide 2 Bharathwaj Muthuswamy Example Circuit R2 VIN R1 VT AVT C VOUT A 100 R1 100 000 Ohms R2 1000 Ohms C 10 uF EE100 Summer 2008 Slide 3 Bharathwaj Muthuswamy Example Circuit R2 VIN R1 VT AVT C VOUT A 100 R1 100 000 Ohms R2 1000 Ohms C 10 uF EE100 Summer 2008 Slide 4 Bharathwaj Muthuswamy EE100 Summer 2008 Slide 5 Bharathwaj Muthuswamy Magnitude in dB Bode Plot Label as dB VOUT A VIN 1 j R2C A 100 R2 1000 Ohms C 10 uF 60 A wp 1 R2C 100 40 20 0 1 10 100 1000 20 Radian Frequency Note Magnitude in dB 20 log10 VOUT VIN EE100 Summer 2008 Slide 6 Bharathwaj Muthuswamy EE100 Summer 2008 Slide 7 Bharathwaj Muthuswamy Phase Example Phase plot VOUT A VIN 1 j R2C A 100 R2 1000 Ohms 180 C 10 uF 90 0 1 10 100 1000 90 180 Radian Frequency 45o Actual value is 100 0 100 0 Phase Phase 0 45 45 1 j 2 45 EE100 Summer 2008 Slide 8 Bharathwaj Muthuswamy Transfer Function Transfer function is a function of frequency Complex quantity Both magnitude and phase are function of frequency Vin Two Port filter network Vout Vout Vout H f out in Vin Vin H f H f EE100 Summer 2008 Slide 9 Bharathwaj Muthuswamy Filters Circuit designed to retain a certain frequency range and discard others Low pass pass low frequencies and reject high frequencies High pass pass high frequencies and reject low frequencies Band pass pass some particular range of frequencies reject other frequencies outside that band Notch reject a range of frequencies and pass all other frequencies EE100 Summer 2008 Slide 10 Bharathwaj Muthuswamy Common Filter Transfer Function vs Freq Magnitude Plots shown H f H f Low Pass High Pass Frequency Frequency H f H f Band Reject Band Pass Frequency EE100 Summer 2008 Frequency Slide 11 Bharathwaj Muthuswamy First Order Lowpass Filter VC 1 j C 1 1 H f tan 1 RC 2 V 1 j C R 1 j RC 1 RC 1 1 Let B and f B 2 RC RC H f H f H f 1 f 1 fB f tan fB 1 2 1 H fB 2 1 2 2 H fB 1 20 log10 2 3 dB 20 log10 H 0 2 EE100 Summer 2008 Slide 12 V R VC C Bharathwaj Muthuswamy EE100 Summer 2008 Slide 13 Bharathwaj Muthuswamy EE100 Summer 2008 Slide 14 Bharathwaj Muthuswamy EE100 Summer 2008 Slide 15 Bharathwaj Muthuswamy First Order Highpass Filter RC VR R j RC H f tan 1 RC 2 V 1 j C R 1 j RC 2 1 RC H f f fB f 1 fB 2 f tan 1 2 fB VR 1 2 1 2 2 H fB 1 20 log10 2 3 dB 20 log10 H 0 2 H fB EE100 Summer 2008 Slide 16 V R VC C Bharathwaj Muthuswamy First Order Lowpass Filter VR 1 1 L tan 1 2 j L V R L 1 1 R R R R Let B and f B L 2 L H f H f H f H f 1 f 1 fB EE100 Summer 2008 f tan fB VR 1 2 V Slide 17 R VL L Bharathwaj Muthuswamy First Order Highpass Filter j L L V L R R H f L tan 1 2 j L V 2 R L 1 1 R R R R Let B and f B 2 L L H f H f V H f f fB f 1 fB EE100 Summer 2008 2 f tan 1 2 fB Slide 18 V R R VL L Bharathwaj Muthuswamy First Order Filter Circuits High Pass VS R C Low Pass Low Pass VS R L High Pass HR R R 1 j C HR R R j L HC 1 j C R 1 j C HL j L R j L EE100 Summer 2008 Slide 19 Bharathwaj Muthuswamy EE100 Summer 2008 Slide 20 Bharathwaj Muthuswamy Diodes OUTLINE Diode Model s Circuit Analysis with Diodes Diode Logic Gates Load Line Analysis Zener Diodes Diode Peak Detector Reading Reader Chapter 2 EE100 Summer 2008 Slide 21 Bharathwaj Muthuswamy Diode Physical Behavior and Equation Schematic Device N P type type Symbol I V V Quantitative I V characteristics Qualitative I V characteristics I V positive easy conduction I I 0 eqV kT 1 V V negative no conduction I In which kT q is 0 026V and IO is a constant depending on diode area Typical values 10 12 to 10 16 A Interestingly the graph of this equation looks just like the figure to the left A non ideality factor n times kT q is often included EE100 Summer 2008 Slide 22 Bharathwaj Muthuswamy Diode Ideal Perfect Rectifier Model The equation I I 0 exp qV kT 1 is graphed below for I 0 10 15 Simple Perfect Rectifier Model A If we can ignore the small forwardbias voltage drop of a diode a simple effective model is the perfect rectifier whose I V characteristic is given below 10 Current in mA 8 6 4 2 Forward Voltage in V I 0 5 0 5 10 The characteristic is described as a rectifier that is a device that permits current to pass in only one direction The hydraulic analog is a check value Hence the symbol I Reverse bias I 0 any V 0 Forward bias V 0 any I 0 V A perfect rectifier V EE100 Summer 2008 Slide 23 Bharathwaj Muthuswamy I V Characteristics I In forward bias on p side we have almost unlimited flow very low resistance Qualitatively the I V characteristics must look like current increases rapidly with V VF I In reverse bias on n side almost no current can flow Qualitatively the I V characteristics must look like The current is close to zero for any negative bias EE100 Summer 2008 Slide 24 VF Bharathwaj Muthuswamy pn Junction Reverse Breakdown As the reverse bias voltage increases the peak electric field in the depletion region increases When the electric field exceeds a critical value Ecrit 2x105 V cm the reverse current shows a dramatic increase reverse leakage current ID A forward current breakdown voltage EE100 Summer 2008 VBD VD V Slide 25 Bharathwaj Muthuswamy The pn Junction I vs V Equation I V characteristic of PN junctions In EECS 105 130 and other courses you will learn …
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