A DC to 42.8 MHz Bandwidth Current Sensor Readout Interface using Amplifiers with Feedforward Compensation for Power Electronics Applications

The switching frequency of the power circuits has reached a few Megahertz range enabled by the silicon carbide and gallium nitride devices. The control circuitry for efficiency enhancement requires current information from sensors with bandwidth in the 10s of Megahertz range. A high bandwidth readout interface is implemented on an application-specific integrated circuit for the hybrid current sensor using amplifiers with a feedforward compensation technique. The amplifiers are designed in the XFAB XT018 process. The 5 V devices are used for the circuit implementation with an input common-mode range of 0 to 4 V. The bandwidth of the single-ended amplifiers is measured to be 40 MHz for 3 V/ V closed-loop gain and 4 MHz for 50 V/ V closed-loop gain. The fully differential amplifiers are also designed using the feedforward compensation technique and the unity gain bandwidth is measured to be 90 MHz with 100 kn input and feedback resistance and 30.8 MHz with 200 kn input and feedback resistance. The readout circuit for the current sensor is measured to generate the final output with 24.08 ns rise time for 0.9 V amplitude.