Electrical cross talk of a frequency division multiplexing readout for a transition edge sensor bolometer array

Area of Science:

• Astrophysics and Space Science
• Electrical Engineering
• Sensor Technology

Background:

• Transition edge sensor (TES) bolometer arrays are crucial for space applications requiring high sensitivity.
• Frequency division multiplexing (FDM) is explored for multiplexing signals from large arrays.
• Electrical cross talk (ECT) is a critical parameter affecting the performance of multiplexed sensor arrays.

Purpose of the Study:

• To characterize and map the electrical cross talk (ECT) in a 61-pixel TES bolometer array using an FDM system.
• To assess the feasibility of FDM technology for space applications by quantifying ECT levels.
• To identify sources of significant ECT and propose mitigation strategies.

Main Methods:

• A modulation technique at 120 Hz was applied to one bolometer's AC bias voltage.
• Simultaneous measurement of cross talk response in the current noise spectra of other bolometers.
• Mapping of ECT across a 61x61 matrix with carrier frequencies from 1 MHz to 4 MHz and 32 kHz spacing.

Main Results:

• Approximately 94% of pixels exhibited ECT levels below 0.4%, with most below 0.1%.
• Adjacent pixels showed the highest ECT levels, reaching up to 0.4%.
• Higher ECT levels (up to 10%) were observed in pixels with bundled, parallel coplanar wires due to high mutual inductance.

Conclusions:

• FDM systems can achieve low ECT levels suitable for space applications, around 0.4% with 30 kHz frequency spacing.
• Bundled coplanar wires are a significant source of ECT and should be replaced with microstrip wires.
• The study successfully demonstrates the potential of FDM technology for low-electrical cross talk space applications.