Vector modulator based active compensation of direct feedthrough

In magnetic particle imaging (MPI), simultaneous excitation and signal acquisition leads to direct feedthrough problems. While this direct-feedthrough can be mitigated up to some extent with passive compensation, this may not be sufficient given the time-variant nature of the system. Active compensation methods are proposed to overcome this challenge. In magnetic resonance imaging (MRI), we have recently proposed a promising active compensation technique that uses a vector modulator-like structure to modify a copy of the transmitted signal and use it for subtracting the direct-feedthrough in analog domain. In this work, this technique is adapted to MPI for active compensation of the direct-feedthrough. We demonstrate a significant increase in detection sensitivity at the fundamental harmonic on an in-house arbitrary waveform relaxometer.