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.

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?