An On-chip DC to 42.8 MHz Bandwidth Readout Interface for Hybrid Current Sensor

A readout interface of a hybrid current sensor is implemented on an application specific integrated circuit to achieve wide bandwidth and higher resolution. The readout interface is implemented in the XFAB 180 nm SOI process. It amplifies the outputs from a low and a high frequency sensor and aggregates their response in an appropriate proportion in the frequency domain to achieve a flat wideband response. The system bandwidth of DC - 42.8 MHz is achieved. The amplifiers are compensated using the feedforward technique, which does not compromise bandwidth for stability. The output step response of 2.51 V amplitude is achieved with 19.84 ns of rise time in response to sensed step current of 10 A amplitude and 5 ns rise time. Hence, the measured sensitivity of the hybrid sensor with an on-chip readout interface is 251 mV/A. In comparison to the on-board readout implementation using commercial components, system bandwidth has increased by a factor of 4.25 in a similar test setup.