Berkeley ELENG 40 - Lecture Notes (31 pages)

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Lecture Notes



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Lecture Notes

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Pages:
31
School:
University of California, Berkeley
Course:
Eleng 40 - Introduction to Microelectronic Circuits
Introduction to Microelectronic Circuits Documents
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EE40 Lec 18 Diode Circuits Reading Chap Reading Chap 10 of Hamble Hambley Supplement Reading on Diode Circuits http www inst eecs berkeley edu ee40 fa09 handouts EE40 http www inst eecs berkeley edu ee40 fa09 handouts EE40 MOS Circuit pdf MOS Circuit pdf EE40 Fall 2009 Slide 1 Prof Cheung Diodes Circuits Load Line Analysis y Analysis of Diode Circuits by assumed states Diode Logic Circuits Wave Shaping Circuits Rectifying Rectifying Circuits EE40 Fall 2009 Slide 2 Prof Cheung SOLVING CIRCUITS WITH NONLINEAR ELEMENTS Look at circuits with a nonlinear element like this IL INL Nonlinear Linear circuit VL VNL element A nonlinear element with its own I V relationship attached to a linear circuit with its own I V relationship 1 2 3 4 IL fL VL INL gNL VNL INL IL VNL VL EE40 Fall 2009 linear circuit I V relationship nonlinear element I V relationship Slide 3 Prof Cheung SOLVING CIRCUITS WITH NONLINEAR ELEMENTS The 4 equations can be reduced to 2 equations in INL and VNL INL fL VNL the linear loadline INL gNL VNL which we can equate and solve for VNL or graph the two equations and solve for the intersection EE40 Fall 2009 Slide 4 Prof Cheung EXAMPLE 1 k 2V IL INL VL V NL 1 IL VL 2 1000 2 Given I0 10 15 A Find VNL VNL 0 026 15 INL 10 e 1 3 INL IIL 3 4 VNL VL Substitute 1 and 2 in 3 10 15 e VNL 0 026 1 VNL 2 1000 Solve by iteration VNL 0 725V EE40 Fall 2009 Slide 5 Prof Cheung Graphical Solution 0 004 linear nonlinear 0 0035 0 003 Loadline I V 2 1000 0 0025 I NL 0 002 0 0015 0 001 0 0005 Diode I V 0 0 725V 0 0005 0 001 1 0 5 0 0 5 1 V NL EE40 Fall 2009 Slide 6 Prof Cheung Piecewise linear Model of Nonlinear Devices 5 5V intercept 1 5V intercept Segment A i v 400 Segment g B i v 1 5 100 Segment C i v 5 5 800 EE40 Fall 2009 Slide 7 Prof Cheung Ideal Diode Model of PN Diode Circuit symbol ID I V characteristic ID A VD Switch model ID forward bias reverse bias VD VD V Diode behaves like a switch closed in forward bias mode open in reverse bias mode used when voltage of interest 0 6V EE40 Fall 2009 Slide 8 Prof Cheung Piecewise Linear Model Circuit symbol ID I V characteristic ID A VD Switch model ID forward bias reverse bias VDon VD V VDon VD For a Si pn diode VDon 0 6 V Diode behaves like a voltage source in series with a switch closed in forward bias mode open iin reverse bias bi mode d EE40 Fall 2009 Slide 9 Prof Cheung Zener Diode A Zener diode is designed to operate in the breakdown mode reverse leakage l k currentt breakdown voltage ID A VBD forward current VD V vs t 15V for all t vs t VBD 15V EE40 Fall 2009 t R Slide 10 vo t integrated circuit i it Prof Cheung Piecewise linear Model of a Zener Diode EE40 Fall 2009 Slide 11 Prof Cheung Diode Circuit Analysis by Assumed Diode States 1 Specify Ideal Diode Model or Piecewise Linear Diode Model ID A ID A forward bias forward bias reverse bias VD V reverse bias VDon 2 Each diode can be ON or OFF 3 Circuit containing n diodes will have 2n states 4 The combination of states that works for ALL di d consistent diodes i t t with ith KVL andd KCL will ill be b the th solution EE40 Fall 2009 Slide 12 Prof Cheung Example Analysis by assumed Diode States D1 on D2 on 1 75mA 0 5mA D1 off D2 on 3 10 D1 off D2 off 0 10 3 D1 on D2 off 6 3 EE40 Fall 2009 Slide 13 Prof Cheung Transfer Function of Diode Circuits Piecewise Linear Model with 0 6V voltage drop EE40 Fall 2009 Slide 14 Prof Cheung Diode Logic AND Gate AND gate Piecewise Linear Model with 0 6V voltage drop Vcc RAND A VOUT C Inputs A and B vary between 0 Volts low and Vcc high Between what voltage levels does C vary with VCC 5V 5 B Output O t t voltage lt C is i hi high h only if both A and B are high EOC Slope 1 Shift 0 7V Up 0 0 EE40 Fall 2009 Slide 15 5 VIN Prof Cheung Diode Logic OR Gate OR gate Piecewise Linear Model with 0 6V voltage drop Inputs A and B vary between 0 V lt low Volts l and d Vcc high hi h Between what voltage levels does C vary with VCC 5V A B C VOUT ROR 5 EOC Output voltage C is high if either or both A and B are high Slope 1 Shift 0 7V Down 0 0 EE40 Fall 2009 Slide 16 0 7V 5 Prof Cheung VIN Diode Logic Incompatibility and Decay Signal Decays with each stage Not regenerative AND gate OR gate output voltage is high only if both A and B are high output voltage is high if either or both A and B are high Vcc A RAND A B EE40 Fall 2009 B CAND COR ROR 0 6V drop Slide 17 Prof Cheung Clipper Circuits Assume forward diode has 0 voltage drop EE40 Fall 2009 Slide 18 Prof Cheung Peak Detector Circuit Assume the ideal perfect rectifier model Vi t Vi t C Vi VC t t Idea The capacitor charges h d due tto one way current behavior of the diode EE40 Fall 2009 VC t Slide 19 VC Prof Cheung Peak Detector with Load Resister EE40 Fall 2009 Slide 20 Prof Cheung Level Shift Circuit VIN C VC VIN VC t VOUT VOUT 1 3 VOUT VC VIN 2 1 Diode open VC 0 VOUT VIN 2 Diode short VC VIN VOUT 0 3 Diode open open VC V VIN min VOUT VIN VC EE40 Fall 2009 Slide 21 Prof Cheung t Clamp Circuit level shifter Max of vin t 5 sin t is shifted by 5V b the by h di diode voltage d l source combination EE40 Fall 2009 Slide 22 Prof Cheung Voltage Doubler Circuit C1 R1 VIN VOUT R2 VOUT C2 VC21 VIN VC1 Peak Detect Level Shift See Homework problem Output is the peak to peak voltage of the input input EE40 Fall 2009 Slide 23 Prof Cheung Half Wave Rectifier Equivalent circuit V 0 6V diode short circuit Vo VI 0 6 06 V 0 6V diode open p circuit Vo 0 EE40 Fall 2009 Slide 24 Prof Cheung Adding a capacitor what does it do Vm sin t C R V0 EE40 Fall 2009 Slide 25 Prof Cheung Half Wave Rectifier Current charging up capacitor EE40 Fall 2009 Slide 26 Prof Cheung Full Wave Rectifier EE40 Fall 2009 Slide 27 Prof Cheung Small Signal Linear Equivalent Circuit Suppose the nonlinear device has the functional dependence I i v is biased with …


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