Cryogenic amplifiers for Jansky Very Large Array receivers

The Very Large Array (VLA) has been recently renamed the Jansky Very Large Array (JVLA) to honor Karl Jansky, the founder of radio astronomy. It has been undergoing a major expansion since 2001 to improve both the frequency coverage and sensitivity. This project previously known as Expanded VLA (EVLA) required new designs of cryogenic amplifiers to provide continuous coverage from 1 GHz to 50 GHz in eight bands with possible best noise temperature. This paper describes the device models and design approach used, provides examples of measured and modeled results, and presents repeatability of measured performance on large samples of amplifiers. These amplifiers in majority of the bands exhibit the best noise performance ever demonstrated at these frequencies, typically about five times the quantum noise hf/k, when measured at physical temperatures of 15-20 K.