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# Voltage controlled oscillators

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### Voltage controlled oscillators

1. 1. Voltage-Controlled Oscillators ECE 453 Final Project • Lih Feng Cheow (lc259) • Chien Chern Khor (ck245) • Sining Qi (sq24)
2. 2. Introduction Voltage-controlled oscillators  Oscillation frequency function of control voltage Implemented 6 VCOs  3 Ring, 3 LC  Discuss 5 Metrics for comparison  Frequency tuning range  Output amplitude  Power consumption  Linearity of frequency-voltage relationship
3. 3. Oscillators & Ring Oscillators VX = | H ( jω ) | V0 + | H ( jω ) |2 V0 + | H ( jω ) |3 V0 + ... | H ( jω ) | ≥ 1 ∠ H ( jω ) = 180 deg • Odd number of gain stages in loop • At least 3 stages • Must collectively satisfy Barkhausen conditions above
4. 4. Differential Ring Oscillatorwith Variable Resistance
5. 5. Variable Resistance: Simulation WaveformsVcontrol Range: 0.58 – 1.75 V Output Amplitude: 0-2.5 VTuning Range: 130 MHz – 4.41 Power Consumption: 16.3 mWGHz
6. 6. Variable Resistance:Frequency vs. Control Voltage Frequency vs Control Voltage 5 4.5 4 3.5 Frequency (GHz) 3 2.5 2 1.5 1 0.5 0 0 0.5 1 1.5 2 Control Voltage (V)
7. 7. Differential Ring Oscillatorwith Delay Interpolation
8. 8. Delay Interpolation:Single Stage
9. 9. Delay Interpolation: Simulation WaveformsVcontrol Range: 1.25 – 1.75 V Output Amplitude: 0 – 2.5 VTuning Range: 554 MHz – 1.5 Power Consumption: 12.5 mWGHz
10. 10. Delay Interpolation:Frequency vs. Control Voltage Frequency vs Control Voltage 1.6 1.4 1.2 Frequency (GHz) 1 0.8 0.6 0.4 1 1.2 1.4 1.6 1.8 2 Control Voltage (V)
11. 11. Negative Resistance
12. 12. Negative Resistance:Cross Coupled Pair
13. 13. LC Oscillator withCross-Coupled NMOS-PMOS
14. 14. Cross-Coupled NMOS-PMOS: Simulation WaveformsVcontrol Range: 0 – 1.3 V Output Amplitude: 0 – 2.5 VTuning Range: 2.24 GHz – 2.6 Power Consumption: 3.185 mWGHz
15. 15. Cross-Coupled NMOS-PMOS:Frequency vs. Control Voltage Frequency vs Control Voltage 2.65 2.6 2.55 2.5 Frequency (Hz) 2.45 2.4 2.35 2.3 2.25 2.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Control Voltage (V)
16. 16. LC Oscillator withCapacitive SourceDegeneration
17. 17. Capacitive Source Degeneration: Simulation WaveformsVcontrol Range: 0 – 2.5 V Output Amplitude: 0 – 2.5 VTuning Range: 2.04 GHz – 2.53 GHz Power Consumption: 7.885 mW
18. 18. Capacitive Source DegenerationFrequency vs. Control Voltage Frequency vs Control Voltage 2.6 2.5 2.4 Frequency (Hz) 2.3 2.2 2.1 2 0 0.5 1 1.5 2 2.5 Control Voltage (V)
19. 19. Differential Ring Oscillatorwith Negative Resistance −2 RN = gm −1 Rp Rout = R p // = gm 1 − gm Rp ↑ I1 ↑ gm ↑ Rout ↑ output time constant ↓ f osc
20. 20. Negative Resistance:Schematic
21. 21. Negative Resistance:Simulation Waveforms Vcontrol Range: 1.3 – 1.5 V Output Amplitude: 0 – 2.5 V Tuning Range: 1.2 GHz – 1.9 GHz Power Consumption: 7.5 mW
22. 22. Negative Resistance:Frequency vs. Control Voltage Frequency vs Control Voltage 2 1.9 1.8 1.7 Frequency (GHz) 1.6 1.5 1.4 1.3 1.2 1.1 1 0.95 1 1.05 1.1 1.15 1.2 1.25 Control Voltage (V)
23. 23. Conclusion Oscillator Topology Tuning Range Vcontrol Power (% from center) Differential Ring Oscillator with 0.13 – 4.41 GHz 0.58 – 1.75 V 16.3 mW Variable Resistor (100%) Differential Ring Oscillator with 0.55 – 1.5 GHz 1.25 – 1.75 V 12.5 mW Delay Interpolation (46%) Differential Ring Oscillator with 1.2 – 1.9 GHz 1.3 – 1.5 V 7.5 mW Negative Resistance (23%) LC Oscillator with 2.16 – 2.82 GHz 0 – 2.2 V 11.41 mWNMOS Only Cross-coupled Pair (13%) LC Oscillator with 2.24 – 2.6 GHz 0 – 1.3 V 3.185 mWNMOS-PMOS Cross-coupled Pair (7%) LC Oscillator with 2.04 – 2.53 GHz 0 – 2.5 V 7.885 mWCapacitive Source Degeneration (11%)
24. 24. Questions?