Broadband microwave integrated circuits for voltage standard applications.

摘要

This thesis addresses integrated circuit component, packaging, and microwave design for both AC and DC Josephson voltage standard (JVS) systems. The components developed in this work combine techniques from both the distributed and lumped-element microwave design in the frequency range 0--40 GHz. The National Institute of Standards and Technology (NIST) JVS systems rely on 10 000 to 300 000 micro-fabricated Josephson junctions (JJs) in superconducting niobium on a silicon substrate at 4 K. This work focuses on both monolithically integrating specialized microwave devices with this JJ fabrication technology as well as enhancing the microwave performance of other system components.Improved microwave packages for JVS circuits developed in this work have increased operating margins, reliability, and longevity of both AC and DC JVS systems. Monolithically-integrated, broadband, lumped-element dividers with bandwidth exceeding 15--22 GHz were designed and fabricated to uniformly distribute power to arrays of Josephson junctions, an enabling technology for the NIST 10V programmable JVS system. Monolithic-microwave-integrated-circuit (MMIC) bias-tees, corners, JJ arrays, and terminations have all been redesigned in this work to improve JVS system operations. To deliver the microwave excitation to the JJs a broadband, MMIC, distributed amplifier was designed and tested with 3--18 GHz bandwidth. These increases in the bandwidth and microwave power on-chip have paved the way for enhanced current and future NIST JVS systems. iii