Noise-optimized ultrastable low-noise current amplifier

Area of Science:

• Electrical Engineering
• Metrology
• Quantum Electronics

Background:

• Accurate current measurements are crucial in various scientific and industrial applications.
• Existing low-noise current amplifiers face limitations in reducing uncertainty at very low current levels.
• Advancements in amplifier design are needed to meet the demands of high-precision measurements.

Purpose of the Study:

• To develop and characterize a noise-optimized ultrastable low-noise current amplifier (ULCA).
• To reduce measurement uncertainty for low current levels.
• To evaluate the stability and performance of the novel ULCA design.

Main Methods:

• Implementation of a thin-film resistor network with a high-ohmic path (6.75 GΩ).
• Conducting noise investigations, short-term, and long-term stability studies.
• Measuring input current gain stability using a cryogenic current comparator (±6.1 nA).
• Developing and verifying methods for low input current accuracy (≈100 pA) below 10⁻⁷ uncertainty.

Main Results:

• Achieved a reduced noise level of 1.6 fA/√Hz.
• Demonstrated stability of the input current gain.
• Verified measurement accuracy at low input currents.
• The noise-optimized ULCA shows improved performance compared to the 2014 standard variant.

Conclusions:

• The noise-optimized ULCA successfully reduces the noise floor without compromising transresistance stability.
• This development enhances measurement accuracy at low currents.
• The novel ULCA design offers significant improvements for precision current metrology.