Extremely low noise integrated charge sensitive amplifiers for electrostatic influence based detectors for cosmic and terrestrial dust
Astrophysics and Astronomy
Final Report Abstract
Improving the sensitivity of charge based dust detectors for cosmic dust was the primary goal of this project. At the same time we intended to significantly extend the range of velocities, at which particles could be detected. For achieving these goals several integrated charge sensitive amplifiers were designed, that operate either in the frequency range from 7 Hz to 300 kHz or in the range from 1 kHz to 50 MHz. The results were demonstrated with a newly developed differential dust detector. Significant progress was achieved in the area of the systematic analysis and optimization of particle detectors. A system model allows for the concurrent optimization of the geometry of the detector and the parameters of the input transistor of the charge sensitive amplifier, assuming that an ideal filter system is in place. This enables us to consider the dependencies between the previously separately designed components of the charge detection system during the optimization of the system. The results show, that, given a fixed detector size and an ideal filter system, the length of an electrode has only a small influence on the detectability of a particle but longer electrodes require a significantly higher power consumption in a matched charge sensitive amplifier. Concerning the developed charge sensitive amplifiers, first measurements showed that the flicker noise of the system is dominated by the noise of the dielectric components of the measurement setup. On-chip dielectrics already seem to increase the noise of the amplifier. Even the optimized measurement setup for the low frequency range with low loss dielectrics shows a noise power that is 9 dB higher than the originally targeted value. A further reduction of flicker noise by circuit design measures was investigated and turned to be extremely difficult. Using switched biasing for the input transistors is the only potentially functional technique known to the authors to reduce the flicker noise in charge sensitive amplifiers. The potential of this measure was evaluated using a test circuit taped out in the technology with the best flicker noise behavior available to the authors. The results show, that in this case the flicker noise can be reduced by 1.7 dB. Due to the limited potential, this method was not further investigated. In conclusion the newly developed amplifiers and detector significantly improves the detectability especially of particles at low velocities in regard to the state of the art. Further work should first focus on improvements of the construction of the system, especially with regard to the dielectric components of the PCB and the detector, acoustic noise coupling to the electrodes and the design of the electrodes and shielding. Additionally, especially adapted semiconductor technologies could potentially further reduce the noise of charge sensitive amplifiers for the considered detection systems.
Publications
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"A Fully Differential Charge-Sensitive Amplifier for Dust-Particle Detectors," 2018 14th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME), 2018, pp. 13-16
S. Kelz, T. Veigel, M. Grözing and M. Berroth
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" Experimental Investigation of Dielectric Loss Induced Noise in Charge Detection Systems for Cosmic Dust," 2021 16th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME), 2021
S. Kelz, M. Grözing and M. Berroth
