We present an X-band amplifier concept based on a HTS grain boundary dc SQUID, which allow for extended dynamic range for use with SIS mixers, e.g., as a buffer amplifier in front of an RSFQ ADC, or possibly for satellite and cellular phone communications. The proposed rf design is based on a combination of single-layer slot and coplanar lines forming novel input and output circuits. The following parameters (per stage) are obtained via simulation for central frequency 11 GHz: bandwidth 0.5-1 GHz, power gain 11-12 dB, noise temperature 5-10 K. A saturation product as high as 500-1000 K(.)GHz is estimated for a characteristic voltage of 1-2 mV. The realization of these parameters makes HTS SQA competitive with existing coolable HEMT-amplifiers for radio astronomy and satellite communication.
Ieee Transactions on Applied Superconductivity, 2003, Vol 13, Issue 2, p. 1046-1049