Frequency allocation using a single VCO
View Patent ↗An apparatus and method to use a single voltage controlled oscillator (VCO) to generate frequencies to cover multiple frequency bands. The single VCO generates local oscillator signals for more than one frequency band of a communication standard or protocol, such as the IEEE 802.11 standard.
1. An apparatus comprising:
a voltage controlled oscillator (VCO) to generate a VCO output having a frequency F VCO ; and
a divider network coupled to the VCO to generate a first oscillator signal having a first oscillator frequency for operating on a first band of frequencies of a 802.11 communication standard and to generate a second oscillator signal having a second oscillator frequency for operating on a second band of frequencies of the 802.11 communication standard, wherein F CH is a channel frequency of the 802.11 standard, in which the first oscillator frequency is determined by a relationship of F CH =1.5 F VCO and the second oscillator frequency is determined by a relationship of F CH =¾F VCO .
2. The apparatus of claim 1 wherein the first oscillator signal is applied to a band of frequencies of a 802.11 a communication standard and the second oscillator signal is applied to a band of frequencies of 802.11 b and 802.11 g communication standards.
3. An apparatus comprising:
a voltage controlled oscillator (VCO) to generate a VCO output having a frequency F VCO ;
a first divide by two circuit coupled to receive the VCO output and to perform a divide by two operation to output a ½ F VCO signal;
a mixer coupled to receive the VCO output of F VCO and ½ F VCO signal and to mix and generate a 1.5 F VCO signal at the mixer output as a first oscillator signal; and
a second divide by two circuit coupled to receive the 1.5 F VCO signal from the mixer and to perform a divide by two operation to output a ¾ F VCO signal as a second oscillator signal.
4. The apparatus of claim 3 wherein the first oscillator signal is applied to one band of frequencies of a 802.11 communication standard and the second oscillator signal is applied to another band of frequencies of the 802.11 communication standard.
5. The apparatus of claim 3 wherein the first oscillator signal is applied to a band of frequencies of a 802.11 a communication standard and the second oscillator signal is applied to a band of frequencies of 802,11 b and 802.11 g communication standards.
6. The apparatus of claim 3 wherein the first and second oscillator frequencies correspond to channel frequencies of a 802.11 communication standard.
7. The apparatus of claim 3 wherein F CH is a channel frequency of the 802.11 standard, in which the first oscillator frequency is determined by a relationship of F CH =1.5 F VCO to provide oscillator frequencies for 802.11a and the second oscillator frequency is determined by a relationship of F CH =¾ F VCO to provide oscillator frequencies for 802.11b and 802.11g.
8. The apparatus of claim 7 wherein F VCO is in the approximate range of 3.2 to 3.9 GHz, the first oscillator signal has a frequency in the approximate range of 4.9 to 5.9 GHz and the second oscillator signal has a frequency in the approximate range of 2.4 to 2.5 GHz.
9. The apparatus of claim 7 wherein the first and second oscillator signals each include in-phase I and quadrature Q components.
10. A method comprising:
generating a voltage controlled oscillator (VCO) output having a frequency F VCO ;
dividing by two the VCO output to generate a ½ F VCO signal;
mixing the VCO output of F VCO and the ½ F VCO signal to generate a 1.5 F VCO signal as a first oscillator signal; and
dividing by two the 1.5 F VCO signal to generate a ¾ F VCO signal as a second oscillator signal.
11. The method of claim 10 further including applying the first oscillator signal to one band of frequencies of a 802.11 communication standard and the second oscillator signal to another band of frequencies of the 802.11 communication standard.
12. The method of claim 11 further including applying the first oscillator signal to a band of frequencies of a 802.11 a communication standard and the second oscillator signal to a band of frequencies of 802,11 b and 802.11 g communication standards.
13. The method of claim 12 wherein F VCO is in the approximate range of 3.2 to 3.9 GHz, the first oscillator signal has a frequency in the approximate range of 4.9 to 5.9 GHz and the second oscillator signal has a frequency in the approximate range of 2.4 to 2.5 GHz.
14. The method of claim 13 further including generating in-phase I and quadrature Q components for the first and second oscillator signals.