| Description: | Low Noise Amplifiers (LNAs) are important components as the first stage in astronomical receiver systems, crucial to achieve high sensitivity systems. Below 10 K noise temperatures have so far only been obtained with cryogenically cooled LNAs, e.g. with < 5 K noise temperature at L‑band, achieving ~25 K system temperature. New systems like Apertif and the SKA aperture array concept are too big and complex for cryogenic cooling. Therefore room temperature solutions using LNAs with extremely low noise temperature are required. Present day semi‑conductor technologies now allow minimum device noise temperatures (Tmin) below 10 K. Using the OMMIC D007IH 70 nm GaAs process, we have designed an LNA with a noise temperature below 10 K across the 1‑2 GHz frequency band. This particular design uses a cascode input stage, which combines low noise performance and good input power matching. The lay‑out of the LNA‑chip is shown in the first displayed photograph, while the second shows the chip in the prober measurement set‑up. The resulting noise temperature is shown on the last plot. This design has been optimized for a 150 ohm input impedance.
These results are very promising for realization of the sensitivity requirements for Apertif, as well as application in the aperture array concept of the SKA. |
