Performance Improvement of Integrated HEB-MMIC Receivers for Multi-Pixel Terahertz Focal Plane Arrays

Phonon-cooled NbN HEB mixers have been successfully integrated with InP MMIC IF amplifiers to produce low-noise HEB-MMIC receivers. Noise temperatures of less than 1,600 K and receiver noise temperature bandwidths of at least 4 GHz (measured at 1.6 THz) have earlier been demonstrated for this type of integrated receivers. Our configuration eliminates the need for isolators which require very large areas on the IF circuit. In this paper, we are presenting recent results from ongoing measurements of these integrated receivers. We propose using different matching schemes for the MMIC LNA that will help reduce the size of the IF circuitry. Small circuit size is a desirable feature for focal plane arrays. Next, we propose a linear terahertz FPA with an increased number of HEB pixels based on the integrated miniaturized design. Lastly, we describe a frequency multiplexing scheme formulated to significantly reduce the number of IF lines required in a large imaging array. The proposed multiplexing scheme utilizes the very broad bandwidth (12 GHz) presently demonstrated for MMIC low-noise IF amplifiers.