Applied Electronics (Analog) chapter-2.pdf
- 2. Load Load- -Line Analysis Line Analysis The load line plots all possible combinations of diode current (ID) and voltage (VD) for a given circuit. The maximum ID equals E/R, and the maximum VD equals E. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 2 2 The point where the load line and the characteristic curve intersect is the Q-point, which identifies ID and VD for a particular diode in a given circuit.
- 3. Series Diode Configurations Series Diode Configurations Constants • Silicon Diode: VD = 0.7 V • Germanium Diode: VD = 0.3 V Analysis (for silicon) Forward Bias Forward Bias Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky • VD = 0.7 V (or VD = E if E < 0.7 V) • VR = E – VD • ID = IR = IT = VR / R 3 3
- 4. Series Diode Configurations Series Diode Configurations Diodes ideally behave as open circuits Analysis • VD = E • VR = 0 V Reverse Bias Reverse Bias Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky R • ID = 0 A 4 4
- 5. Parallel Configurations Parallel Configurations V .7 V 10 D V E V 9.3 R V V 0.7 O V D2 V D1 V V 0.7 D V − − = = = = = Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 5 5 mA 14 2 mA 28 D2 I D1 I mA 28 .33kΩ V .7 V 10 R D V E R I = = = = − = − =
- 6. Half Half- -Wave Rectification Wave Rectification The diode only conducts when it is forward biased, therefore only half of the AC cycle passes through the Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 6 6 passes through the diode to the output. The DC output voltage is 0.318Vm, where Vm = the peak AC voltage.
- 7. PIV (PRV) PIV (PRV) Because the diode is only forward biased for one-half of the AC cycle, it is also reverse biased for one-half cycle. It is important that the reverse breakdown voltage rating of the diode be high enough to withstand the peak, reverse-biasing AC voltage. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 7 7 PIV (or PRV) > Vm • PIV = Peak inverse voltage • PRV = Peak reverse voltage • Vm = Peak AC voltage
- 8. Full Full- -Wave Rectification Wave Rectification The rectification process can be improved by using a full-wave rectifier circuit. Full-wave rectification produces a greater DC output: Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 8 8 • Half-wave: V Vdc dc = 0.318 = 0.318V Vm m • Full-wave: V Vdc dc = 0.636 = 0.636V Vm m DC output:
- 9. Full Full- -Wave Rectification Wave Rectification Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 9 9 Bridge Rectifier Bridge Rectifier • Four diodes are connected in a bridge configuration • VDC = 0.636Vm
- 10. Full Full- -Wave Rectification Wave Rectification Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 10 10 Center Center- -Tapped Transformer Tapped Transformer Rectifier Rectifier Requires • Two diodes • Center-tapped transformer VDC = 0.636Vm
- 11. Summary of Rectifier Circuits Summary of Rectifier Circuits Rectifier Rectifier Ideal Ideal V VDC DC Realistic Realistic V VDC DC Half Wave Rectifier VDC DC = 0.318Vm VDC DC = 0.318Vm m – 0.7 Bridge Rectifier VDC DC = 0.636Vm VDC DC = 0.636Vm – 2(0.7 V) Center-Tapped Transformer V = 0.636V V = 0.636V – 0.7 V Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 11 11 Vm = peak of the AC voltage. I In the center tapped transformer rectifier circuit, the peak AC voltage is the transformer secondary voltage to the tap. Center-Tapped Transformer Rectifier VDC DC = 0.636Vm VDC DC = 0.636Vm – 0.7 V
- 12. Diode Clippers Diode Clippers • The diode in a series clipper series clipper “clips” any voltage that does not forward bias it: •A reverse-biasing polarity •A forward-biasing polarity less than 0.7 V (for a silicon diode) Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 12 12
- 13. Biased Clippers Biased Clippers Adding a DC source in series with the clipping diode changes the effective forward bias of the diode. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 13 13
- 14. Parallel Clippers Parallel Clippers The diode in a parallel clipper parallel clipper circuit “clips” any voltage that forward bias it. DC biasing can be added in series with the diode to change Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 14 14 series with the diode to change the clipping level.
- 15. Summary of Clipper Circuits Summary of Clipper Circuits Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 15 15 more… more…
- 16. Summary of Clipper Circuits Summary of Clipper Circuits Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 16 16
- 17. Clampers Clampers A diode and capacitor can be combined to “clamp” an AC signal to a specific DC level. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 17 17
- 18. Biased Clamper Circuits Biased Clamper Circuits The input signal can be any type of waveform such as sine, square, and triangle waves. The DC source lets you adjust the DC camping level. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 18 18 the DC camping level.
- 19. Summary of Clamper Circuits Summary of Clamper Circuits Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 19 19
- 20. Zener Diodes Zener Diodes The Zener is a diode operated in reverse bias at the Zener Voltage (Vz). • When Vi ≥ ≥ ≥ ≥ VZ – The Zener is on Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 20 20 – Voltage across the Zener is VZ – Zener current: IZ = IR – IRL – The Zener Power: PZ = VZIZ • When Vi < VZ – The Zener is off – The Zener acts as an open circuit
- 21. Zener Resistor Values Zener Resistor Values ZK R L I I I − = min min max L Z L I V R = If R is too large, the Zener diode cannot conduct because the available amount of current is less than the minimum current rating, IZK. The minimum current is given by: The maximum value of resistance is: Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 21 21 min max L Z L L L R V R V I = = Z i Z L V V RV R − = min If R is too small, the Zener current exceeds the maximum current rating, IZM . The maximum current for the circuit is given by: The minimum value of resistance is:
- 22. Voltage Voltage- -Multiplier Circuits Multiplier Circuits • Voltage Doubler • Voltage Tripler • Voltage Quadrupler Voltage multiplier circuits use a combination of diodes and capacitors to step up the output voltage of rectifier circuits. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 22 22
- 23. Voltage Doubler Voltage Doubler This half-wave voltage doubler’s output can be calculated by: Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 23 23 This half-wave voltage doubler’s output can be calculated by: Vout = VC2 = 2Vm where Vm = peak secondary voltage of the transformer
- 24. Voltage Doubler Voltage Doubler • Positive Half-Cycle o D1 conducts o D2 is switched off o Capacitor C1 charges to Vm • Negative Half-Cycle o D1 is switched off o D2 conducts o Capacitor C charges to V Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 24 24 o Capacitor C2 charges to Vm Vout = VC2 = 2Vm
- 25. Voltage Tripler and Quadrupler Voltage Tripler and Quadrupler Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky 25 25
- 26. Practical Applications Practical Applications • Rectifier Circuits – Conversions of AC to DC for DC operated circuits – Battery Charging Circuits • Simple Diode Circuits – Protective Circuits against – Overcurrent – Polarity Reversal Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 • All rights reserved. Electronic Devices and Circuit Theory, 10/e Robert L. Boylestad and Louis Nashelsky – Polarity Reversal – Currents caused by an inductive kick in a relay circuit • Zener Circuits – Overvoltage Protection – Setting Reference Voltages 26 26