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An ultra-low noise bipolar current source



Ian Spielman, Alessandro Restelli, Mingshu Zhao, Junheng Tao, Qiyu Liang


The precise control of dc magnetic fields is crucial in wide range of experimental platforms, from ultracold quantum gases, nuclear magnetic resonance, to precision measurements. In each of these cases the Zeeman effect causes quantum states to shift in energy as a function of magnetic field. The development of low noise current sources is essential because electromagnets are the preferred tool to dynamically control the magnetic field. Here we describe an ultra-low noise bipolar current source using pairs of complementary n- and p-channel MOSFETS controlled by zero-drift operational amplifiers. Our source has an $90\ \rm kHz}$ bandwidth and provides current from \SI-20}\ampere} to \SI20}\ampere} with short-term noise (\SI10}\Hz} to \SI200}k\Hz}) of $6.8\ \rm ppm}}$ at $\pm\SI20}\ampere}$. In our application this controlled dc magnetic fields with an inductively limited \SI9}k\Hz}} bandwidth and short-term noise (\SI20}\Hz} to \SI9}k\Hz}) $2\ \rm ppm}}$ at $\pm\SI20}\ampere}$.
Review of Scientific Instruments


Lab Instrumentation, power supply, opamp, quantum


Spielman, I. , Restelli, A. , Zhao, M. , Tao, J. and Liang, Q. (2023), An ultra-low noise bipolar current source, Review of Scientific Instruments, [online], (Accessed July 15, 2024)


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Created June 6, 2023, Updated February 2, 2024