In general, phase noise in designing a voltage controlled oscillator is one of important indicators indicating oscillation performance. As phase noise is better, stability of an oscillator is increased. This phase noise has been known to be affected by a quality factor Q of a resonator. The quality factor of a resonator refers to selectivity characteristics of a particular frequency. Having a high quality factor means that a frequency may be selected sharply in a sense of narrowband. That is, frequency selectivity in a voltage controlled oscillator is enhanced.
Among voltage controlled oscillators, a voltage controlled oscillator using a split ring resonator (SRR) having meta-material characteristics is fabricated such that the SRR is installed on a printed circuit board (PCB). Such a voltage controlled oscillator has a high quality factor and represents excellent phase noise characteristics or performance. However, the voltage controlled oscillator has a problem in that it has a considerably large area relative to an integrated circuit type voltage controlled oscillator.
The integrated circuit type voltage controlled oscillator advantageously has a very small area. However, this has a limitation in lowering phase noise most critical to the voltage controlled oscillator.