Voltage controlled oscillators
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The document summarizes six voltage-controlled oscillator (VCO) circuits implemented in a final electronics project. Three of the VCOs use ring oscillator topologies with variable resistance, delay interpolation, and negative resistance. The other three use LC oscillator topologies with a cross-coupled NMOS pair, cross-coupled NMOS-PMOS pair, and capacitive source degeneration. Simulation results show the tuning range, output amplitude, power consumption, and linearity of the frequency-voltage relationship for each VCO. The differential ring oscillator with variable resistance achieved the widest tuning range from 130 MHz to 4.41 GHz but with the highest power consumption of 16.3 mW.
Voltage controlled oscillators
- 1. Voltage-Controlled Oscillators ECE 453 Final Project • Lih Feng Cheow (lc259) • Chien Chern Khor (ck245) • Sining Qi (sq24)
- 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. 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. Differential Ring Oscillator with Variable Resistance
- 5. Variable Resistance: Simulation Waveforms Vcontrol Range: 0.58 – 1.75 V Output Amplitude: 0-2.5 V Tuning Range: 130 MHz – 4.41 Power Consumption: 16.3 mW GHz
- 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. Differential Ring Oscillator with Delay Interpolation
- 9. Delay Interpolation: Simulation Waveforms Vcontrol Range: 1.25 – 1.75 V Output Amplitude: 0 – 2.5 V Tuning Range: 554 MHz – 1.5 Power Consumption: 12.5 mW GHz
- 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)
- 12. Negative Resistance: Cross Coupled Pair
- 13. LC Oscillator with Cross-Coupled NMOS-PMOS
- 14. Cross-Coupled NMOS-PMOS: Simulation Waveforms Vcontrol Range: 0 – 1.3 V Output Amplitude: 0 – 2.5 V Tuning Range: 2.24 GHz – 2.6 Power Consumption: 3.185 mW GHz
- 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. LC Oscillator with Capacitive Source Degeneration
- 17. Capacitive Source Degeneration: Simulation Waveforms Vcontrol Range: 0 – 2.5 V Output Amplitude: 0 – 2.5 V Tuning Range: 2.04 GHz – 2.53 GHz Power Consumption: 7.885 mW
- 18. Capacitive Source Degeneration Frequency 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. Differential Ring Oscillator with Negative Resistance −2 RN = gm −1 Rp Rout = R p // = gm 1 − gm Rp ↑ I1 ↑ gm ↑ Rout ↑ output time constant ↓ f osc
- 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. 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. 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 mW NMOS Only Cross-coupled Pair (13%) LC Oscillator with 2.24 – 2.6 GHz 0 – 1.3 V 3.185 mW NMOS-PMOS Cross-coupled Pair (7%) LC Oscillator with 2.04 – 2.53 GHz 0 – 2.5 V 7.885 mW Capacitive Source Degeneration (11%)
- 24. Questions?