  We experimentally demonstrate the principle of an on-chip submillimeter wave
filter bank spectrometer, using superconducting microresonators as narrow
band-separation filters. The filters are made of NbTiN/SiNx/NbTiN microstrip
line resonators, which have a resonance frequency in the range of 614-685
GHz---two orders of magnitude higher in frequency than what is currently
studied for use in circuit quantum electrodynamics and photodetectors. The
frequency resolution of the filters decreases from 350 to 140 with increasing
frequency, most likely limited by dissipation of the resonators.
