RF Filter Circuit With λ/4 Choke for Compact Plasma Power Feed

The patent transitions from a conventional linear filter structure to a three-dimensional cavity resonator structure. The housing forms a closed cavity with specific dimensional ratios (length:width:height = 3:2:1) that create resonant frequencies to block radio-frequency interference. This spatial arrangement in multiple dimensions achieves filtering functionality without requiring complex circuit components.

The patent optimizes the physical dimensions of the housing cavity to achieve desired filtering characteristics. By adjusting the length, width, and height of the cavity according to specific ratios and absolute dimensions, the resonant frequencies are tuned to block specific radio-frequency bands. This parameter optimization allows the same compact structure to filter different frequencies by simply changing dimensional parameters.

The patent combines the filter housing with the power feed line structure itself. The housing serves dual purposes: it contains the cavity resonator for filtering radio-frequency interference and simultaneously acts as the protective enclosure for the power feed line. This merging of functions eliminates the need for separate filter housing and power feed line enclosures, reducing overall volume.

The housing structure performs multiple functions simultaneously: it provides mechanical protection for the power feed line, forms the cavity resonator for radio-frequency filtering, and serves as the mounting structure for the electrostatic chuck. This multi-functionality reduces the number of separate components needed, achieving compact design without compromising filtering performance.