Gain and Noise in THz MgB2 Hot-Electron Bolometer Mixers With a 30-K Critical Temperature

In this paper, we study variation of the MgB
₂
hotelectron bolometer mixer characteristics such as noise temperature, gain, output noise, and local oscillator (LO) power at 5-, 15-, and 20-K bath temperatures, and at 0.69and 1.63-THz LO frequencies. The main reason for the noise temperature rising at higher temperatures is a reduction of the mixer gain, which occurs proportionally to the LO power reduction. Contrary to this, the output noise remains constant (for the same bias point).