Chopping for over 50 MHz gain‐bandwidth product current sense amplifiers achieving input noise level of 8.5 nV/√Hz

Abstract An accurate, high‐speed, fully differential difference amplifier for current sensing utilizing the chopper approach was implemented in a 0.18 μm complementary metal‐oxide‐semiconductor (CMOS) technology. Unlike state‐of‐the‐art solutions, we use higher chopping frequency MHz range due to bandwidth requirements of introduced circuits latter application, namely, low‐side phase‐current measurement motor control circuits. Except low‐pass filter (LPF) effect output stage, no additional LPF integrated hardware at We show that on other hand digital LPF, which can be field‐programmable gate‐array (FPGA) logic or microcontroller used control, offers flexibility terms design. Weak input signals only few mV reconstructed with high accuracy. This is demonstrated 500 kHz rectangular signal and 20 MHz. Note an input‐signal several hundreds harmonics region very challenging amplifiers. Still, significant decrease input‐referred noise demonstrated, especially cancelling out 1/ f ‐noise achieving remaining floor approximately 8.5 nV/√Hz. Overall, level pushed far below 50 μV (root mean square). Moreover, using quite relaxed second‐order Butterworth 3 dB corner 1 MHz, levels 10 square) easily achieved costs reduced bandwidth. The lowest offset μV. gain adjusted by resistive feedback 40 dB. Hence, suitable circuits, reduction shunt resistance typically this purpose will possible.