Gain bandwidth and noise characteristics of millimeter-wave YBa2Cu3O7 hot-electron bolometer mixers

Conversion gain bandwidth and noise characteristics are reported for lattice-cooled superconducting YBa2Cu3O7 hot-electron bolometers acting as low-power, wide-bandwidth heterodyne mixers at 75 and 585 GHz. Near 77 K, these mixers show intrinsic conversion gain as high as −16 dB using ∼1 μW of local oscillator power. The measured gain bandwidth is well described by a single Lorentzian with −3 dB frequency of 5–9 GHz. Measurements of output noise combined with conversion gain indicate an optimal input noise temperature of ∼5000 K, significantly lower than calculations predict.