QUANTUM NOISE CONTRIBUTION TO THE RECEIVER NOISE TEMPERATURE OF HEB THZ HETERODYNE RECEIVERS

In this paper we discuss the quantum limit of bolometric mixer receivers. The importance of the optics attenuation is emphasized. Based on a simple bolometer model we predict that the system and receiver quantum noise limits referred to the input of a double-sideband hotelectron bolometer mixer receiver are, respectively, 2(h113) and 1 (hf/3). The quantum limit to the DSB receiver noise temperature is hf/2k, in agreement with what has previously often been assumed. We suggest that an image-rejection single-sideband version of the HEB mixer would have a system quantum noise limit of WO). We also suggest that at a frequency of several THz the quantum noise may indeed be responsible for about half the total receiver noise temperature in a typical HEB receiver system.