Ultrastable Low-Noise Current Amplifiers With Extended Range and Improved Accuracy

The ultrastable low-noise current amplifier (ULCA) was developed as an advanced instrument for the improved measurement of currents generated by single-electron transport (SET) devices. It was optimized for direct currents in the picoampere range, and achieves an uncertainty of <inline-formula> <tex-math notation="LaTeX">$<0.1~\mu \text{A}$ </tex-math></inline-formula>/A for a current of 100 pA typically generated by SET pumps. This paper summarizes our efforts in extending the ULCA’s current range and minimizing the measurement uncertainty over a wide range. Two ULCA variants with improved short-term uncertainty of about 0.02 <inline-formula> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula>/A or improved noise level of 1.4 fA/<inline-formula> <tex-math notation="LaTeX">$\sqrt {\text {Hz}}$ </tex-math></inline-formula> are presented. Combining these devices allows the construction of a novel standard for direct currents below 50 <inline-formula> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula>, which has superior performance to previous methods for small-current generation or measurement. ULCAs involving thick-film resistors achieve noise levels down to 0.43 fA/<inline-formula> <tex-math notation="LaTeX">$\sqrt {\text {Hz}}$ </tex-math></inline-formula>. A low-bias variant features an effective input bias current within ±100 aA and a temperature coefficient within ±10 aA/K, which enables uncertainties below 10 aA in direct current measurements without reversing or switching ON/OFF the signal current.

[1]  G-D Willenberg.  EUROMET.EM-S24: Supplementary comparison of small current sources , 2013 .

[2]  Ralf Behr,et al.  Validation of a quantized-current source with 0.2 ppm uncertainty , 2015, 1506.05965.

[4]  Luca Callegaro,et al.  Techniques for Traceable Measurements of Small Currents , 2007, IEEE Transactions on Instrumentation and Measurement.

[5]  F. Ahlers,et al.  Ultrastable low-noise current amplifier: a novel device for measuring small electric currents with high accuracy. , 2015, The Review of scientific instruments.

[6]  Dietmar Drung,et al.  Improved calibration of instruments for small direct currents , 2016, 2016 Conference on Precision Electromagnetic Measurements (CPEM 2016).

[7]  Dietmar Drung,et al.  A compact 14-bit cryogenic current comparator , 2014, 29th Conference on Precision Electromagnetic Measurements (CPEM 2014).

[8]  Yu. A. Pashkin,et al.  Single-electron current sources: towards a refined definition of ampere , 2012, 1208.4030.

[9]  Dietmar Drung,et al.  Improving the Traceable Measurement and Generation of Small Direct Currents , 2015, IEEE Transactions on Instrumentation and Measurement.

[10]  B. Camarota,et al.  Quantum metrology triangle experiments: a status review , 2012, 1204.6500.

[11]  Gert Rietveld,et al.  Accurate subpicoampere current source based on a differentiating capacitor with software-controlled nonlinearity compensation , 2005, IEEE Transactions on Instrumentation and Measurement.

[12]  Dietmar Drung,et al.  Ultrastable low-noise current amplifiers with extended range and improved accuracy , 2016, 2016 Conference on Precision Electromagnetic Measurements (CPEM 2016).

[13]  Non-adiabatic quantized charge pumping with tunable-barrier quantum dots: a review of current progress , 2009 .

[14]  Dietmar Drung,et al.  Validation of the ultrastable low-noise current amplifier as travelling standard for small direct currents , 2015, 1507.00127.

[15]  P. Warnecke,et al.  A traceable precision current source for currents between 100 aA and 10 pA , 2002, CPEM 2002.

[16]  D Drung,et al.  Measurement of sub-picoampere direct currents with uncertainties below ten attoamperes. , 2017, The Review of scientific instruments.

[17]  D. Ritchie,et al.  Towards a quantum representation of the ampere using single electron pumps , 2012, Nature Communications.

[18]  Jonathan M. Williams,et al.  New Capability for Generating and Measuring Small DC Currents at NPL , 2007, IEEE Transactions on Instrumentation and Measurement.