Apparatus and method of oscillating wideband frequency
An apparatus and method of oscillating a wideband frequency are disclosed. The apparatus includes: a frequency oscillating unit for oscillating a predetermined frequency; a phase-locked loop for comparing the oscillated frequency and a reference frequency by feed-backing the oscillated frequency from the frequency oscillating unit and fixing an oscillating frequency of the frequency oscillating unit; and a variable dividing unit for varying a division ratio to approach to a frequency band required by the oscillating frequency and dividing the oscillating frequency.
1. An apparatus for oscillating a frequency, comprising: frequency.
a phase-locked loop circuit which generates a first frequency signal;
a variable frequency divider which divides the first frequency signal by a division ratio to generate a second frequency signal that lies within a predetermined frequency band,
a first detector in the phase-locked loop circuit to compare a first reference frequency signal and the second frequency signal;
a second detector to compare a second reference frequency signal and at least a third frequency signal;
a first controller to control the division ratio of the variable frequency divider based on a result of the comparison of the second reference frequency signal and at least the third frequency signal performed by the second detector; and
a second controller to adjust a voltage-controlled oscillator of the phase-locked loop circuit to control the first frequency signal, wherein the first controller varies the second frequency signal by a first amount and the second controller varies the second frequency signal by a second amount to cause the second frequency signal to lie within said predetermined frequency band.
2. The apparatus of claim 1 , wherein the voltage-controlled oscillator includes:
a resonating circuit; and
an active circuit which oscillates a signal output from the resonating circuit to form the first frequency signal, the second controller adjusting a parameter of the resonating circuit to adjust the second frequency signal by said second amount.
3. The apparatus of claim 2 , wherein the the parameter is a capacitance value of the resonating circuit which is varied based on an applied voltage.
4. The apparatus of claim 1 , wherein the resonating circuit includes:
a plurality of LC tank circuits for generating resonant frequencies;
a switching circuit for selecting one of the LC tanks to generate the first frequency signal.
5. A method for oscillating a frequency, comprising:
generating a first frequency signal from a phase-locked loop;
dividing the first frequency signal by a division ratio to generate a second frequency signal that lies within a predetermined frequency band, the division ratio being varied based on a comparison of a reference frequency signal and feedback frequency signal input into the phase-locked loop;
comparing a first reference frequency signal and the second reference frequency signal using a first detector;
comparing a second reference frequency signal and at least a third frequency signal using a second detector;
controlling the division ratio based on a result of the comparison of the second reference frequency signal and at least the third frequency signal; and
adjusting a voltage-controlled oscillator of the phase-locked loop to control the first frequency signal wherein controlling the division ratio varies the second frequency signal by a first amount and adjusting the voltage-controlled oscillator varies the second frequency signal by a second amount to cause the second frequency signal to lie within said predetermined frequency band.
6. The method of claim 5 , wherein the voltage-controlled oscillator includes:
a resonating circuit; and
an active circuit which oscillates a signal output from the resonating circuit to form the first frequency signal. said adjusting including adjusting a parameter of the resonating circuit to adjust the second frequency signal by said second amount.
7. The method of claim 6 , wherein the parameter is a capacitance value which is varied based on an applied voltage.
8. The method of claim 5 , wherein the resonating circuit includes:
a plurality of LC tank circuits for generating resonant frequencies;
a switching circuit for selecting one of the LC tanks to generate the first frequency signal.
9. The apparatus of claim 1 , wherein the first reference frequency signal is equal to the second reference frequency signal.
10. The apparatus of claim 1 , wherein the first controller and second controller are different circuits.
11. The apparatus of claim 1 , wherein the second frequency signal is divided by a fixed value before being compared by the first detector.
12. The apparatus of claim 1 , wherein the third frequency signal corresponds to a minimum frequency of said predetermined frequency band, the first controller increasing the division ratio of the variable frequency divider when the minimum frequency is greater than the second reference frequency signal to lower the second frequency signal to a value which lies within said band.
13. The apparatus of claim 12 , wherein, if the minimum frequency is less than the second reference frequency signal, the first controller compares the second reference frequency signal to a fourth frequency signal which corresponds to a maximum frequency of said predetermined frequency band, the first controller reducing the division ratio of the variable frequency divider when the maximum frequency is less than the second reference frequency signal to increase the second frequency signal to a value which lies within said band.
14. The apparatus of claim 1 , wherein the third frequency signal corresponds to an average frequency of said predetermined frequency band.
15. The apparatus of claim 1 , wherein the third frequency signal is based on the second frequency signal.
16. The apparatus of claim 1 , wherein the second frequency signal corresponds to an output frequency of the phase-locked loop circuit, said phase-locked loop circuit included in a tuner of a communication device which generates a baseband signal or RF signal based on the output frequency.
17. The method of claim 5 , wherein the first reference frequency signal is equal to the second reference frequency signal.
18. The method of claim 5 , wherein the second frequency signal is divided by a fixed value before being compared to the first reference frequency signal.
19. The method of claim 5 , wherein the third frequency signal corresponds to a minimum frequency of said predetermined frequency band and wherein said controlling includes:
increasing the division ratio when the minimum frequency is greater than the second reference frequency signal to lower the second frequency signal to a value which lies within said band.
20. The method of claim 19 , wherein, if minimum frequency is less than the second reference frequency signal, said method further includes:
comparing the second reference frequency signal to a fourth frequency signal corresponding to a maximum frequency of said predetermined frequency band; and
reducing the division ratio when the maximum frequency is less than the second reference frequency signal to increase the second frequency signal to a value which lies within said band.
21. The method of claim 5 , wherein the third frequency signal corresponds to an average frequency of said predetermined frequency band.
22. The method of claim 5 , wherein the third frequency signal is based on the second frequency signal.
23. The method of claim 5 , wherein the second frequency signal corresponds to an output frequency of the phase-locked loop circuit, said phase-locked loop circuit included in a tuner of a communication device which generates a baseband signal or RF signal based on the output frequency.