Diplexer Design Implementing Highly Miniaturized Multilayer Superconducting Hybrids and Filters

Multilayer superconducting quadrature hybrids for diplexer applications are reported for the first time in this paper. The hybrids employ highly miniature lumped element components embedded within four metal layers. The thin dielectric layers between the metal layers and the small feature size of the process allow for the miniaturization of lumped element capacitors and inductors. Hybrid-coupled diplexers using lumped element hybrids and filters have been developed, fabricated, and tested. A novel filter configuration that employs inter-resonator tap connections is also demonstrated for implementation in wideband filter applications. The whole integrated high Q (quality factor) diplexer is highly miniaturized being approximately lambda₀ /60 in size at a frequency of 1.0 GHz. The diplexer structures are amenable to superconductor microelectronics technology and can be integrated monolithically with a superconducting receiver on a single chip.