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Signal Generators

Signal Generators. Oscillators. HW: Due Friday Nov. 9 13.4,13.14,13.23,13.27 . SIGNAL GENERATORS /OSCILLATORS. A positive-feedback loop is formed by an amplifier and a frequency-selective network. In an actual oscillator circuit, no input signal will be present.

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Signal Generators

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  1. Signal Generators Oscillators November 2, 2007

  2. HW: Due Friday Nov. 9 13.4,13.14,13.23,13.27 November 2, 2007

  3. SIGNAL GENERATORS /OSCILLATORS A positive-feedback loop is formed by an amplifier and a frequency-selective network In an actual oscillator circuit, no input signal will be present November 2, 2007

  4. Oscillator-frequency stability November 2, 2007

  5. Limiter Ckt Comparator November 2, 2007

  6. Wien-bridge oscillator without amplitude stabilization. November 2, 2007

  7. Wien bridge w/ Amp. Stabil. limiter used for amplitude control. November 2, 2007

  8. Alternate Wien bridge stabil. November 2, 2007

  9. Phase Shift Oscillator November 2, 2007

  10. Phase Shift. Osc. W/ Stabil. November 2, 2007

  11. Quad Osc. Circuit November 2, 2007

  12. Active Tuned Osc. November 2, 2007

  13. OPAMP based Tuned Amp. Osc. November 2, 2007

  14. Colpitts and Hartley Oscillators November 2, 2007

  15. Equiv. Ckt To simplify the analysis, negtlect Cm and rp Consider Cp to be part of C2, and include ro in R. November 2, 2007

  16. Collpits Oscillator November 2, 2007

  17. Piezzoelectric Crystal November 2, 2007

  18. Pierce Oscillator CMOS inverter as an amplifier. November 2, 2007

  19. Bistable Operation November 2, 2007

  20. Bistable November 2, 2007

  21. November 2, 2007

  22. Hysteresis November 2, 2007

  23. Noisy Signal November 2, 2007

  24. Limiter (b)L+ = VZ + VD1 + VD2 and L– = –(VZ + VD3 + VD4). a) L+ = VZ1 + VD and L– = –(VZ2 + VD), Limiter circuits = more precise output levels for bistable circuit. R according to current required for the proper operation of the zener diodes. November 2, 2007

  25. Astable w/ feedback Abistable multivibrator with inverting transfer characteristics in a feedback loop with an RC circuit results in a square-wave generator. November 2, 2007

  26. Astable The circuit obtained when the bistable multivibrator is implemented with the circuit (This circuit is called an astable multivibrator.) c) Waveforms at various nodes of the circuit in (b). November 2, 2007

  27. Ckt for triang/square wave A general scheme for generating triangular and square waveforms. November 2, 2007

  28. (a) An op-amp monostable circuit. (b) Signal waveforms in the circuit of (a). November 2, 2007

  29. 555 IC internal circuit of the 555 integrated-circuit timer. November 2, 2007

  30. 555 for monostable a) The 555 timer connected to implement a monostable multivibrator. (b) Waveforms of the circuit in (a). November 2, 2007

  31. 555 for astable • The 555 timer connected to implement an astable multivibrator. (b) Waveforms of the circuit in (a). November 2, 2007

  32. Triangle  Sinusoid Using a nonlinear (sinusoidal) transfer characteristic to shape a triangular waveform into a sinusoid. November 2, 2007

  33. (a) A three-segment sine-wave shaper. (b) The input triangular waveform and the output approximately sinusoidal waveform. November 2, 2007

  34. A differential pair with an emitter degeneration resistance used to implement a triangular-wave to sine-wave converter. November 2, 2007

  35. Superdiode when vI> 0 and the diode conducts, the op amp supplies the load current, and the source is conveniently buffered, an added advantage. (a) The “superdiode” precision half-wave rectifier and (b) its almost ideal transfer characteristic. November 2, 2007

  36. An improved version of the precision half-wave rectifier: Diode D2 is included to keep the feedback loop closed around the op amp during the off times of the rectifier diode D1, thus preventing the op amp from saturating. • The transfer characteristic for R2 = R1. November 2, 2007

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