TES Bolometers With High-Frequency Readout Circuit

In order to improve the frequency-division multiplexing (FDM) in transition edge sensor (TES) imaging arrays, it is suggested to replace commonly used SQUID amplifiers with a semiconductor high-frequency cooled amplifier. This would result in a single 10-GHz bandwidth amplifier serving the array of more than 1000 detectors. The basic idea is to implement an antenna-coupled TES as a load for a high-Q resonator, weakly coupled to a microwave transmission line. This high-frequency scheme substitutes the traditional wire connections to the TES. The NEP as low as 2×10^-19 W/Hz^0.5 is estimated at ambient temperature of 300 mK for submicron-size TES absorber made of Ti; the NEP is limited by 3 K noise temperature of the amplifier. To verify the new concept, prototype TES devices made of Nb are developed and tested above 4 K. The NEP of about 1.5×10^-15 W/Hz^0.5 is estimated for the experimental micron-size prototype devices made of Nb at 4.5 K. The IV -curves of the TES at different temperatures are recovered using the RF and heat balance models along with the experimental R(T) data; presence of the negative electrothermal feedback is verified.