Quadrature local oscillator signal generation systems and methods
A quadrature based voltage controlled oscillator (VCO) local oscillator (LO) system is disclosed. The system includes a phase detector, a quadrature phase VCO, a quadrature control path, an in-phase control path, and an in-phase VCO. The phase detector is configured to compare and generate phase error between a reference clock and an in-phase VCO output. The quadrature control path configured to generate a quadrature control voltage based on a quadrature VCO output and the in-phase VCO output. The quadrature phase VCO configured to generate the quadrature VCO output based on the quadrature control voltage and the generated phase error. The in-phase control path configured to generate an in-phase control voltage based on the quadrature VCO output and the in-phase VCO output. The in-phase VCO is configured to generate the in-phase VCO output based on the in-phase control voltage and the generated phase error. An all digital dual mode phase locked/phase tracking loop LO generate system is also disclosed.
1. A quadrature based voltage controlled oscillator (VCO) based local oscillator (LO) generator system comprising:
a phase detector configured to compare a reference clock and an in-phase VCO output and generate a phase error based on the comparison;
a quadrature control path configured to generate a quadrature control voltage based on a quadrature VCO output and the in-phase VCO output;
a quadrature phase VCO configured to generate the quadrature VCO output based on the quadrature control voltage and the generated phase error;
an in-phase control path configured to generate an in-phase control voltage based on the quadrature VCO output and the in-phase VCO output; and
an in-phase VCO configured to generate the in-phase VCO output based on the in-phase control voltage and the generated phase error.
2. The system of claim 1 , wherein the quadrature VCO includes a varactor based fine frequency control configured to modify the quadrature VCO output based on the generated phase error.
3. The system of claim 1 , wherein the quadrature VCO includes a varactor based fine frequency control configured to modify the quadrature VCO output based on the quadrature control voltage.
4. The system of claim 1 , wherein the in-phase VCO includes a varactor based fine frequency control configured to modify the in-phase VCO output based on the generated phase error.
5. The system of claim 1 , wherein the in-phase VCO includes a varactor based fine frequency control configured to modify the in-phase VCO output based on the in-phase control voltage and a second varactor based fine frequency control configured to modify the in-phase VCO output based on the generated phase error.
6. The system of claim 1 , wherein the quadrature control path includes a quadrature phase detector configured to generate the quadrature control voltage based on a comparison of the quadrature VCO output and the in-phase VCO output.
7. The system of claim 1 , wherein the in-phase control path includes an in-phase phase detector configured to generate the in-phase control voltage based on a comparison of the quadrature VCO output and the in-phase VCO output.
8. The system of claim 1 , further comprising transconductors configured to integrate detected phase errors to generate the quadrature control voltage and the in-phase control voltage.
9. The system of claim 8 , wherein the phase errors comprise a quadrature phase error based on the output of the quadrature VCO output passed through a pass gate driven by the in-phase VCO output.
10. The system of claim 8 , wherein the phase errors comprise an in-phase phase error based on the output of the in-phase VCO output passed through a pass gate driven by the quadrature VCO output.
11. The system of claim 1 , further comprising loop filters configured to generate the quadrature and in-phase control voltages.
12. The system of claim 1 , wherein the quadrature control path is configured to generate negative feedback due to image rejection of a quadrature phase detector.
13. The system of claim 1 , wherein the in-phase VCO includes a varactor based fine frequency control configured to modify the in-phase VCO output based on the in-phase phase control voltage.
14. The system of claim 1 , further comprising:
transconductors configured to integrate detected phase errors to generate the quadrature control voltage and the in-phase control voltage; and
loop filters configured to configured to provide a filtering of the generated quadrature control voltage and the in-phase control voltage.