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

8. Delay Interpolation:
Single Stage

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)

11. Negative Resistance

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

20. Negative Resistance:
Schematic

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?