Filter-bank for Broadband Sub-mm Wave Superconducting On-chip Spectrometers [VIDEO]
A. Pascual Laguna (TU Delft - Electrical Engineering, Mathematics and Computer Science)
K. Karatsu (TU Delft - Electrical Engineering, Mathematics and Computer Science)
D. J. Thoen (TU Delft - Electrical Engineering, Mathematics and Computer Science)
V. Murugesan (SRON–Netherlands Institute for Space Research)
A. Endo (TU Delft - Electrical Engineering, Mathematics and Computer Science)
J. J. A. Baselmans (TU Delft - Electrical Engineering, Mathematics and Computer Science)
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Abstract
DESHIMA 2.0 is a broadband sub-mm wave superconducting on-chip spectrometer for astronomy, targeting an instantaneous octave bandwidth (220 - 440 GHz) sampled with moderate spectral resolution channels (f/df ~ 500). In this work we propose a microstrip filter-bank implementation for DESHIMA 2.0 based on “H-shaped” resonators. These bandpass filters are free from spurious resonances over an octave bandwidth, do not suffer from radiation losses and can be arrayed in large filter-banks thanks to their extremely low reflections off-resonance. The design has been aided by an analytical circuit model that can fast and reliably predict the filter-bank behaviour. Prototype chips have been characterised in terms of frequency response and coupling efficiency.