Disrupting the RF and Microwave Industry with a Patented Ceramic Gap Capacitor

The Eulex Gap Capacitor, a novel solution developed by Quantic™ Eulex, is poised to disrupt the RF and microwave industry. This patented design addresses the limitations of traditional single-layer capacitors (SLCs) and offers significant performance and cost advantages.

Limitations of Single-Layer Capacitors

Single-layer wire-bondable ceramic capacitors have been the industry standard, but they come with several drawbacks:

• Capacitance limitations: The capacitance of SLCs is largely dependent on the dielectric constant of the materials used, requiring manufacturers to develop an extensive selection of dielectric materials to overcome this limitation.
• Awkward physical integration: SLCs do not lend themselves well to surface mount techniques, often requiring wire bonding, which can be expensive and unreliable, especially at higher frequencies.
• Attempts to circumvent wire bonding, such as attaching tab leads or standing the device on end, add cost and complexity to the assembly without addressing the capacitance limitations.
• A number of companies have developed gap capacitors under various trademark names. Gap capacitors are essentially 2 single-layer capacitors in series. The device is soldered or epoxy mounted to the strip line, completely eliminating the need for a wire bond. The widths are designed to match standard strip-line widths, an excellent solution for both strip-line and co-planar waveguide designs. However, these devices do not overcome the capacitance limitations of the SLC. As a matter of fact, these devices exacerbate this limitation, as the series capacitance generates a value C/2 (or half) of the original SLC device being replaced. The added complexity of the second metalized surface and the configuration of the electrodes move these devices further away from the ideal capacitor configuration.

The Eulex Gap Capacitor Solution

The patented Eulex Gap Capacitor addresses these issues with a novel internal structure that produces a true single-layer capacitor without the need for wire bonding.

Figure 1. Depiction of Non-Wire Bonding Structure of Eulex Gap Capacitor.

 Key advantages of the Eulex Gap Capacitor include:

• Increased Capacitance: As the configuration of the electrodes generates more capacitance from the same dielectric material, the Eulex Gap Capacitor can achieve up to 20 times more capacitance than competitors' designs.
• Simplified Dielectric Selection: The Eulex Gap Capacitor covers the full range of capacitance requirements using only three dielectrics, compared to up to 26 dielectrics required by competitors.
• Elimination of Wire-Bonding: The Eulex Gap Capacitor can be flip-chip or surface-mounted, completely eliminating the need for wire-bonding.
• Improved Performance: Independent testing has shown the Eulex gap capacitor maintains excellent performance, with less than 5 dB loss at 1 GHz and less than 1 dB loss at 67 GHz.
• Lower Manufacturing Costs: The efficient design of the Eulex Gap Capacitor results in lower manufacturing costs, which are passed on to customers.

Table 1. Competitor Comparison of Different Capacitors (0804 Size)

Figure 2. Insertion Loss and Return Loss Simulation Results of Different Eulex Gap Capacitors, Tested on 0.02" Thick Roger Board Fixture with 0.008" Gap.

Versatile Applications

The Eulex Gap Capacitor is an excellent solution for a variety of applications, including photonics, synchronous optical networking (SONET), receive and transmit optical sub-assemblies (ROSA/TOSA), trans-impedance amplifiers (TIA), high-speed data, test equipment, and broadband microwave/mm-wave systems. It is also well-suited for strip-line or coplanar wave-guide applications. This capacitor can be used for functional applications such as DC blocking, coupling, RF bypassing, filtering, and tuning.

The Eulex Gap Capacitor's versatility extends beyond its use as a superior alternative to standard gap capacitor applications. It can also be used in the following configurations:

• Binary Capacitor: When mounted upside down or in a flip-chip configuration, the Eulex gap capacitor can be used as a binary capacitor, providing a gap capacitor and two single-layer capacitor connections.
• Broadband Block: The Eulex gap capacitor can be mounted to a high-capacitance multi-layer ceramic capacitor (MLCC) to create a high-performance broadband block with extremely low insertion loss

Conclusion

The Eulex gap capacitor from Quantic Eulex represents a significant advancement in ceramic capacitor technology. By addressing the limitations of traditional SLCs and offering increased performance, simplified dielectric selection, and lower manufacturing costs, the Eulex gap capacitor is poised to disrupt the RF and microwave industry. Its versatile applications further demonstrate the innovative nature of this patented design.