Apparatus and method for multiplying frequency

1. An apparatus for multiplying a frequency of an input signal, comprising:

a main differential device for converting the input signal into a first differential signal and a second differential signal;

a first multiplying device for outputting a first signal obtained by multiplying a frequency of the first differential signal;

a second multiplying device for outputting a second signal obtained by multiplying a frequency of the second differential signal; and

a compositing device for outputting a third signal obtained by combining the first signal and the second signal to remove a fundamental frequency component,

wherein the main differential device is a balun or a transformer.

2. The apparatus of claim 1 , wherein

the first signal and the second signal include the fundamental frequency component and a second harmonic component, and the fundamental frequency components of the first and second signals differ in phase by 180 degrees from each other, and the second harmonic components of the first and second signals are in phase with each other.

3. The apparatus of claim 1 , wherein

the first multiplying device and the second multiplying device are connected in parallel between the main differential device and the compositing device.

4. The apparatus of claim 3 , wherein

the first multiplying device includes a first differential device for converting the first differential signal received from the main differential device into a third differential signal and a fourth differential signal.

5. The apparatus of claim 4 , wherein

the first multiplying device includes a first transistor device for outputting a first rectified signal obtained by half-wave rectifying the third differential signal received from the first differential device and a second rectified signal obtained by half-wave rectifying the fourth differential signal received from the first differential device.

6. The apparatus of claim 5 , wherein

the first multiplying device includes a first summing device for outputting the first signal obtained by combining the first and second rectified signals received from the first transistor device.

7. The apparatus of claim 3 , wherein

the second multiplying device includes a second differential device for converting the second differential signal received from the main differential device into a fifth differential signal and a sixth differential signal.

8. The apparatus of claim 7 , wherein

the second multiplying device includes a second transistor device for outputting a third rectified signal obtained by half-wave rectifying the fifth differential signal received from the second differential device and a fourth rectified signal obtained by half-wave rectifying the sixth differential signal received from the second differential device.

9. The apparatus of claim 8 , wherein

the second multiplying device includes a second summing device for outputting the second signal obtained by combining the third and fourth rectified signal received from the second transistor device.

10. A method for multiplying a frequency of an input signal, comprising:

converting, by a main differential device, the input signal into a first differential signal and a second differential signal;

outputting, by a first multiplying device, a first signal obtained by multiplying a frequency of the first differential signal, and outputting, by a second multiplying device, a second signal obtained by multiplying a frequency of the second differential signal; and

outputting, by a compositing device, a third signal obtained by combining the first signal and the second signal to remove a fundamental frequency component,

wherein the main differential device is a balun or a transformer.

11. The method of claim 10 , wherein,

the outputting the first signal and the second signal comprises:

converting the first differential signal into a third differential signal and a fourth differential signal, and converting the second differential signal into a fifth differential signal and a sixth differential signal; and

outputting a first signal obtained by combining first and second rectified signals obtained by half-wave rectifying the third differential signal and the fourth differential signal, respectively, and outputting a second signal obtained by combining third and fourth rectified signals obtained by half-wave rectifying the fifth differential signal and the sixth differential signal, respectively.

12. The method of claim 10 , wherein

the first multiplying device and the second multiplying device are connected in parallel between the main differential device and the compositing device.

13. An apparatus for multiplying a frequency of an input signal, comprising:

a main differential device for converting the input signal into a first differential signal and a second differential signal;

a first differential device connected to a top of an output terminal of the main differential device, and converting the first differential signal received from the main differential device into a third differential signal and a fourth differential signal;

a second differential device connected to a bottom of the output terminal of the main differential device, and converting the second differential signal received from the main differential device into a fifth differential signal and a sixth differential signal;

a first transistor device connected to an output terminal of the first differential device, and outputting first and second rectified signals obtained by half-wave rectifying the third and fourth differential signals, respectively;

a second transistor device connected to an output terminal of the second differential device, and outputting third and fourth rectified signals obtained by half-wave rectifying the fifth and sixth differential signals, respectively;

a first summing device connected to an output terminal of the first transistor device, and outputting the first signal obtained by combining the first and second rectified signal received from the first transistor device;

a second summing device connected to an output terminal of the second transistor device, and outputting the second signal obtained by combining the third and fourth rectified signals received from the second transistor device; and

a compositing device connected to output terminals of the first summing device and the second summing device, and outputting a third signal obtained by combining the first signal and the second signal to remove a fundamental frequency component.

14. The apparatus of claim 13 , wherein

the main differential device, the first differential device, and the second differential device are baluns or transformers.

15. The apparatus of claim 13 , further comprising:

a first amplifying device connected between the first differential device and the first transistor device, and amplifying the third differential signal and the fourth differential signal; and

a second amplifying device connected between the second differential device and the second transistor device, and amplifying the fifth differential signal and the sixth differential signal.