Reduced phase noise multi-band VCO

1. A multi-band voltage controlled oscillator (VCO) for adjusting a frequency of an output signal based on an input signal, the multi-band VCO comprising:

a tank module comprising a parallel combination of a capacitor and an inductor configured to hold oscillating energy of the output signal, the parallel combination having a positive conductance;

an active module comprising a pair of cross-coupled transistors configured to provide a negative conductance that cancels out the positive conductance; and

a control module configured to adjust a body voltage of the cross-coupled transistors based on the frequency of the output signal to improve a phase noise associated with the output signal.

2. The multi-band VCO of claim 1 , wherein the output signal is taken across the parallel combination of the tank module.

3. The multi-band VCO of claim 1 , wherein the frequency of the output signal is determined based on a resonant frequency of the parallel combination.

4. The multi-band VCO of claim 1 , wherein the capacitor is a tunable capacitive array.

5. The multi-band WO of claim 4 , wherein the capacitor is configured to be tuned based on the input signal.

6. The multi-band VCO of claim 1 , wherein adjusting the body voltage of the cross-coupled transistors changes a magnitude of the negative conductance provided by the active module.

7. The multi-band VCO of claim 1 , wherein the control module is a digital-to-analog converter.

8. A multi-band voltage controlled oscillator (VCO) for adjusting a frequency of an output signal based on an input signal, the multi-band VCO comprising:

a tank module comprising a parallel combination of a capacitor and an inductor configured to hold oscillating energy of the output signal; and

an active module comprising a pair of cross-coupled transistors configured to provide a negative conductance that cancels out a positive conductance associated with the tank module;

wherein a body voltage of the cross-coupled transistors is configured to be adjusted based on the frequency of the output signal to improve a phase noise associated with the output signal.

9. The multi-band VCO of claim 8 , wherein the output signal is taken across the parallel combination of the tank module.

10. The multi-band VCO of claim 9 , wherein the frequency of the output signal is determined based on a resonant frequency of the parallel combination.

11. The multi-band VCO of claim 9 , wherein the capacitor is a tunable capacitive array.

12. The multi-band VCO of claim 11 , wherein the capacitor is configured to be tuned based on the input signal.

13. The multi-band VCO of claim 9 , wherein adjusting the body voltage of the cross-coupled transistors changes a magnitude of the negative conductance provided by the active module.

14. A method for operating a multi-band voltage controlled oscillator (VCO) comprising a tank module configured to hold oscillating energy and an active module configured to provide a negative conductance that cancels out a positive conductance associated with the tank module, the method comprising:

receiving a frequency setting input signal;

adjusting a capacitance of the tank module based on the frequency setting input signal to control a frequency of the oscillating energy; and

adjusting the negative conductance of the active module based on the frequency setting input signal to improve a phase noise associated with the oscillating energy.

15. The method of claim 14 , wherein the adjusting the negative conductance of the active module comprises adjusting a body voltage of a transistor.

16. The method of claim 14 , wherein the adjusting the negative conductance of the active module comprises increasing the negative conductance of the active module if a frequency of the oscillating energy is reduced.

17. The method of claim 14 , wherein the adjusting the negative conductance of the active module comprises decreasing the negative conductance of the active module if a frequency of the oscillating energy is increased.