Basic circuit or cad

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Basic circuit or cad

  1. 1. Basic Circuit Simulation using OrCAD Prof. Anish Goel
  2. 2. Capacitors in Series Series Capacitors add like Parallel Resistors: 1/CT = 1/C1 + 1/Cn CT = .909uF 2 OrCAD Prof. Anish Goel
  3. 3. Capacitors in Parallel Parallel Capacitors add like Series Resistors: CT = C1 + Cn CT = 11uF 3 OrCAD Prof. Anish Goel
  4. 4. Inductors in Series• Series Inductors add like Series Resistors:• LT = L1 + Ln• LT = 11uH4 OrCAD Prof. Anish Goel
  5. 5. Inductors in Parallel Parallel Inductors add like Parallel Resistors: 1/LT = 1/L1 + 1/Ln LT = .909uH 5 OrCAD Prof. Anish Goel
  6. 6. Capacitor Review Starts as short circuit, ends as open circuit iC = C*dVC/dt Open circuit at low frequencies Short circuit at high frequencies 6 OrCAD Prof. Anish Goel
  7. 7. Inductor Review Starts as open circuit, ends as short circuit VL = L*dI/dt Short circuit at low frequencies Open circuit at high frequencies 7 OrCAD Prof. Anish Goel
  8. 8. Filters Use frequency response characteristics of C and L to filter frequency components out of a time domain signal. Low Pass High Pass Band Pass Band Stop 8 OrCAD Prof. Anish Goel
  9. 9. Low Pass Filters RC Low Pass: fcut off frequency = 1/(2πRC) • Component selection • RC vs. RL filters RL Low Pass: fc = R/(2πL)9 OrCAD Prof. Anish Goel
  10. 10. AC Analysis (freq) Logarithmic plot (count by decades) fc defined as –3dB of input, “Half power point” Copy paste data points to excel! 10 OrCAD Prof. Anish Goel
  11. 11. Decibels Measure of gain. Instead of saying gain is 100,000x, some engineers prefer to say it as 100dB. Power gain: dB = 10 log(Po/Pi) Voltage gain: dB = 20 log(Vo/Vi) Always a relationship 11 OrCAD Prof. Anish Goel
  12. 12. Decibels (cont’d) Useful values:  0dB = 1x  3dB = 2x  6dB = 4x  10dB = 10x  20dB = 100x  30dB = 1000x  3dBm is 3dB above 1mW 12 OrCAD Prof. Anish Goel
  13. 13. Cursor Control Cursor 1:  left click  left/right arrows Cursor 2:  right click  Shift left/right arrows 13 OrCAD Prof. Anish Goel
  14. 14. Cursor, Mark Label14 OrCAD Prof. Anish Goel
  15. 15. .707? Because we are comparing gains in voltage, not power, we must use 20log(Vo/Vi). 10^(-3dB/20) = .707V So,Vo = .707Vi at the cut off frequency 15 OrCAD Prof. Anish Goel
  16. 16. Bode Plot (dB, logarithmic)16 OrCAD Prof. Anish Goel
  17. 17. Common Problems Q: Simulation not making sense A: Make sure you how things are connected.17 OrCAD Prof. Anish Goel
  18. 18. • RC High Pass: • RL High Pass:• fc = 1/(2πRC) • fL = R/(2πL)18 OrCAD Prof. Anish Goel
  19. 19. Band Pass HP LP BW = (fc + 3dB) – (fc – 3dB) BW = 200.171kHz – 494.694Hz = 199.676kHz19 OrCAD Prof. Anish Goel
  20. 20. Response20 OrCAD Prof. Anish Goel
  21. 21. Band Stop HP LP BW = 16.216kHz –6.0833kHz = 10.133kHz21 OrCAD Prof. Anish Goel
  22. 22. Response22 OrCAD Prof. Anish Goel
  23. 23. Transformer Easy to “Step down” or “Step up” an AC voltage (This is why AC is used for home power delivery instead of DC.) VP/VS = NP/NS => VS = VPNS/NP Excellent DC filter because VS = NS*dΦ/dt 23 OrCAD Prof. Anish Goel
  24. 24. In PSPICE… Coupling = 1 Lx_Value = Nx2  should be between 1mH and 1H 24 OrCAD Prof. Anish Goel
  25. 25. Diode Allow current to flow only in 1 direction Flow from left (annode+) to right (cathode-) is forward biased. Diode causes a voltage drop due to its activation voltage.  Silicon - .7V  Germanium - .3V Cathode connected to a battery is reversed biased. (blocked) Perform DC Sweep and Transient Response (use D1N4002) 25 OrCAD Prof. Anish Goel
  26. 26. Activation Voltage26 OrCAD Prof. Anish Goel
  27. 27. Transient ResponseHalf Wave Rectifier27 OrCAD Prof. Anish Goel
  28. 28. Half Wave Rectifier28 OrCAD Prof. Anish Goel
  29. 29. Full Wave Rectification29 OrCAD Prof. Anish Goel
  30. 30. Bridge Rectifier30 OrCAD Prof. Anish Goel
  31. 31. In PSPICE…31 OrCAD Prof. Anish Goel
  32. 32. Full Wave Rectifier32 OrCAD Prof. Anish Goel
  33. 33. Smoothing Use capacitor to smooth the ripples of the rectified wave form. (Negative voltage)33 OrCAD Prof. Anish Goel
  34. 34. Regulators Not in student addition Outputs a clean regulated voltage LM317 and 337 are +/- 2-18V variable regulators LM7805 is 5V regulator Input must be relatively steady or else regulator will fail. 34 OrCAD Prof. Anish Goel

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