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Oscillator Circuits

Oscillator Circuits. Outline. Oscillators Inverter-Based Oscillator Introduction of Phase Noise Simulation LC-Tank Based Oscillator Laplace Analysis Circuit Implementation Quality Factor Analysis. Inverter-Based Oscillator. Delay Per Stage of the Inverter. (395 ps ). (273 pS ).

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Oscillator Circuits

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  1. Oscillator Circuits

  2. Outline • Oscillators • Inverter-Based Oscillator • Introduction of Phase Noise Simulation • LC-Tank Based Oscillator • Laplace Analysis • Circuit Implementation • Quality Factor Analysis

  3. Inverter-Based Oscillator

  4. Delay Per Stage of the Inverter (395 ps) (273 pS) Period: 395-273=122 pS, Delay per stage (TD): 234-214=20 pS. Period is 2NTD

  5. Oscillation Frequency Calculation • fosc=2.14 GHz • Tosc=467 pS=2NTD • TD=20 pS • N=Tosc/(2TD)=467 pS/(2 20)=11.68 • N must be odd. • Choose N as 11.

  6. 11 Stage Oscillator

  7. 11 Stage Oscillator Period: 1.501 nS-1.052 nS=0.449 nS, Freq=2.227 GHz

  8. Phase Noise

  9. Periodic Steady State Analysis

  10. Harmonics

  11. Pnoise

  12. Phase Noise of a Ring Oscillator

  13. LC Tank Oscillator

  14. Laplace Transform Analysis

  15. LC Tank Oscillator • Resonant Frequency: 2.14 GHz • L=1 nH • C=5.53 pF (Adjustable)

  16. LC Tank Oscillator

  17. Transient Simulation (Steady state after 10 nS) Frequency: 1.941GHz

  18. Reduce the Value of Capacitor (2.16 GHz)

  19. PSS and Pnoise Setting

  20. Phase Noise

  21. Quality Factor of 10 for the inductor Oscillation dies out since gtankis greater than gm of the transistor.

  22. Rind=100 mΩ This is the maximum parasitic resistance we can have without destroying the oscillation.

  23. Transient Simulation

  24. Phase Noise with Rind=100 mΩ Even a little series resistance at unreasonably high Q (130) can degrade phase noise quickly.

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