A 20 A bipolar current source with 140 <i>μ</i>A noise over 100 kHz bandwidth

The precise control of direct current (dc) magnetic fields is crucial in a wide range experimental platforms, from ultracold quantum gases and nuclear resonance to precision measurements. In each these cases, the Zeeman effect causes states shift energy as function field. development low-noise sources essential because electromagnets are preferred tool dynamically Here, we describe an ultra-low noise bipolar source using pairs complementary n- p-channel metal–oxide–semiconductor field-effect transistors controlled by zero-drift operational amplifiers. Our has 90 kHz inherent bandwidth provides −20 20 A with (0.1 Hz 100 kHz) 140 µA at ±20 A.