Optimization Approaches for the Signal Processing of Hybrid Current Sensors

Hybrid current sensors are suitable devices for wide bandwidth current measurement. They combine two different measurement circuits, one for DC and low-frequency current measurement and another for high frequency current measurement. This combines the advantages of different measurement principles in one current sensor. The output signal of the hybrid current sensor is generated through a superposition of the low-frequency and high-frequency current sensor. This is realized using analog signal processing by means of an analog operational amplifier circuit. The challenge is to superpose the frequency responses of the different measurement circuits achieving a constant gain in the transition area. This paper focuses on the analog signal processing and its optimization. Based on a state-of-the-art realization, two possible optimization approaches of the signal processing are presented to increase the bandwidth. These optimization approaches are investigated in a simulation model and verified by frequency response measurements of a hybrid current sensor based on tunneling magnetoresistance sensors and a Rogowski coil.