HTS miniaturized filter based on mixed resonators integrated with a two-stage low-noise amplifier

In this paper, we report on the fabrication and testing of a superconducting miniaturized filter integrated with a low-noise amplifier (LNA), in a single metallic packaging. The superconducting L-band filter is based on the combined use of dual-mode cross-slotted patch resonators and stepped resonators, and is able to offer a good trade-off between compactness and power handling. As far as the LNA is concerned, a two-stage single-ended configuration is proposed, providing a gain of 28 dB with a flatness of about +/- 0.5 dB all over the bandwidth (15% centred around 2.15 GHz). A double bias scheme has been adopted (separate gate and drain biases) and great care has been taken to ensure stable performances under all possible operating load conditions, therefore ensuring unconditional stability of the amplifying stages. The LNA noise figure at room temperature has been estimated to be under 0.6 dB over the entire operating bandwidth. A superconducting filter integrated with an LNA has been assembled in a single copper package, exhibiting a total space occupation of (40 x 25) mm(2). The final performances have been tested at T = 77 K, showing a gain of about 30 dB and minimum noise figure of 0.47 dB.