Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
Photodiode Preamplifiers
We investigate low-noise preamplifier solutions for LISA which help convert the laser signals into electrical signals.
Photodiode preamplifier PCB (top) connected via a flex section to the photodiode PCB (bottom). Each photodiode features 4 segments, therefore 4 independent preamplifier channels are present in the main board (two visible, two on the bottom side). A coaxial interface is used for each channel's output and the power supply is delivered via a nano-D interface (left-hand side).
Photodiode preamplifier PCB (top) connected via a flex section to the photodiode PCB (bottom). Each photodiode features 4 segments, therefore 4 independent preamplifier channels are present in the main board (two visible, two on the bottom side). A coaxial interface is used for each channel's output and the power supply is delivered via a nano-D interface (left-hand side).
In LISA, the laser signals used for picometer-precision metrology are converted into electrical signals by photodiodes. The faint, picowatt-level amplitudes of those laser signals set stringent constraints on the photodiode preamplifier noise.
We investigate preamplifier solutions based on low-noise, discrete transistors that outperform their OpAmp-based counterparts in terms of noise, bandwidth and power consumption. A transistor-based preamplifier is currently being used in prototype units for the LISA Mission.
The goal of the current prototypes is to achieve a Technology Readiness Level of 6, which means reaching the desired preamplifier performance in realistic mission conditions (thermal-vacuum, vibration, irradiation). Once this readiness level is achieved, our efforts will focus on supporting the design and test of the engineering and flight models of the LISA photodiode preamplifiers.
Literature
1.
Fernandez Barranco, G.; Heinzel, G.: A dc-coupled, HBT-based transimpedance amplifier for the LISA quadrant photoreceivers. IEEE Transactions on Aerospace and Electronic Systems, 3068437 (2021)
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