Low Phase Noise Voltage Controlled Oscillators

Abstract

A voltage controlled oscillator (VCO) with low phase noise and a sharp output spectrum is desirable. The present disclosure provides embodiments of LC tank VCOs that generate output signals with less phase noise compared with conventional LC tank VCOs, while at the same time limiting additional cost, size, and/or power. The embodiments of the present disclosure can be used, for example, in wired or wireless communication systems that require low-phase noise oscillator signals for performing up-conversion and/or down-conversion.

What is claimed is: 
     
         1 . A multi-injection voltage controlled oscillator (VCO) for providing a low phase noise oscillating signal at an output, the multi-injection VCO comprising:
 a first inductor-capacitor tank VCO configured to generate a first oscillating signal;   a second inductor-capacitor tank VCO configured to generate a second oscillating signal; and   an output coupler configured to electrically couple the first oscillating signal to the output using a first transmission line and to electrically couple the second oscillating signal to the output using a second transmission line.   
     
     
         2 . The multi-injection VCO of  claim 1 , wherein the first transmission line is used to form, at least in part, a resonator of the first inductor-capacitor tank VCO, and the second transmission line is used to form, at least in part, a resonator of the second inductor-capacitor tank VCO. 
     
     
         3 . The multi-injection VCO of  claim 1 , wherein the output coupler is configured to provide both the first oscillating signal and the second oscillating signal at the output substantially in-phase with each other. 
     
     
         4 . The multi-injection VCO of  claim 1 , wherein the output coupler is configured to couple the first inductor-capacitor tank VCO to the second inductor-capacitor tank VCO in series or in parallel. 
     
     
         5 . The multi-injection VCO of  claim 1 , wherein the first transmission line has a length that is greater than 1/10 of a wavelength of the first oscillating signal. 
     
     
         6 . The multi-injection VCO of  claim 1 , wherein the first transmission line comprises a ladder line, a stripline, a dielectric slab, or a waveguide. 
     
     
         7 . The multi-injection VCO of  claim 1 , wherein the output coupler is configured to electrically couple the first oscillating signal and the second oscillating signal to the output in parallel using, the first transmission line and the second transmission line. 
     
     
         8 . A multi-band, multi-injection voltage controlled oscillator (VCO), for providing a low phase noise oscillating signal at an output, the multi-band VCO comprising:
 a first cluster of inductor-capacitor tank VCOs configured to generate a first oscillating signal at a first frequency by electrically coupling output oscillating signals generated by a first number of the inductor-capacitor tank VCOs in the first cluster to the output using a first set of transmission lines; and   a second cluster of inductor-capacitor tank VCOs configured to generate a second oscillating signal at a second frequency different from the first frequency by electrically coupling output oscillating signals generated by a second number of the inductor-capacitor tank VCOs in the second cluster to the output using a second set of transmission lines.   
     
     
         9 . The multi-band, multi-injection VCO of  claim 8 , wherein a first transmission line of the first set of transmission lines is used to form a resonator of a first inductor-capacitor tank VCO of the first cluster of inductor-capacitor tank VCOs. 
     
     
         10 . The multi-band, multi-injection VCO of  claim 9 , wherein the first transmission line has a length that is greater than 1/10 of a wavelength of the first oscillating signal. 
     
     
         11 . The multi-band, multi-injection VCO of  claim 9 , wherein the first transmission line comprises a ladder line, a stripline, a dielectric slab, or a waveguide. 
     
     
         12 . The multi-band, multi-injection VCO of  claim 8 , further comprising:
 a controller configured to control the first cluster of inductor-capacitor tank VCOs and the second cluster of inductor-capacitor tank VCOs such that only one of the first cluster inductor-capacitor tank VCOs and the second cluster of inductor-capacitor tank VCOs is on.   
     
     
         13 . The multi-band, multi-injection VCO of  claim 8 , wherein the first number of the inductor-capacitor tank VCOs that are on in the first cluster is adjustable. 
     
     
         14 . The multi-band, multi-injection VCO of  claim 8 , wherein the first number of the inductor-capacitor tank VCOs that are on in the first cluster is adjustable based on a power requirement. 
     
     
         15 . The multi-band, multi-injection VCO of  claim 8 , wherein the first number of the inductor-capacitor tank VCOs that are on in the first cluster is adjustable based on a phase noise requirement. 
     
     
         16 . The multi-band, multi-injection VCO of  claim 8 , wherein the first number of the inductor-capacitor tank VCOs in the first cluster is adjustable based on a signal-to-noise ratio of a signal. 
     
     
         17 . .A multi-injection voltage controlled oscillator (VCO) for providing a low phase noise oscillating signal at an output, the multi-injection VCO comprising:
 a first VCO configured to generate a first oscillating signal using a first tank circuit comprising a parallel combination of a first inductor and a first capacitor;   a second VCO configured to generate a second oscillating signal using a second tank circuit comprising a parallel combination of a second inductor and a second capacitor; and   an output coupler configured to electrically couple the first oscillating signal to the output using a first transmission line and to electrically couple the second oscillating signal to the output using a second transmission line, wherein the first transmission line is used to form, at least in part, the first inductor, and the second transmission line is used to form, at least in part, the second inductor.   
     
     
         18 . The multi-injection VCO of  claim 17 , wherein the output coupler is configured to provide both the first oscillating signal and the second oscillating signal at the output substantially in-phase with each other. 
     
     
         19 . The multi-injection VCO of  claim 17 , wherein the output coupler is configured to couple the first inductor-capacitor tank VCO to the second inductor-capacitor tank VCO in series or in parallel. 
     
     
         20 . The multi-injection VCO of  claim 17 , wherein the first transmission line has a length that is greater than 1/10 of a wavelength of the first oscillating signal.