Op-amp based low noise amplifier for magnetic particle spectroscopy

Magnetic particle spectrometry (MPS) is a novel technique used to measure the magnetization response of superparamagnetic iron oxide nanoparticles (SPIONs). Therefore, it is one of the most important tools for the characterization of the SPIONs for imaging modalities such as magnetic particle imaging (MPI) and Magnetic Resonance Imaging (MRI). In MPS, change in the particle magnetization induces a voltage in a dedicated receive coil. The amplitude of the signal can be very low (ranging from a few nV to 100 µV) depending upon the concentration of the nanoparticles. Hence, the received signal needs to be amplified with a low noise amplifier (LNA). LNA’s paramount task is to amplify the received signal while keeping the noise induced by its own circuitry minimum. In the current research, we purpose modeling, design, and development of a prototyped LNA for MPS. The designed prototype LNA is based on the parallelization technique of Op-amps. The prototyped LNA consists of 16 Op-amps in parallel and is manufactured on a printed circuit board (PCB), with a size of 110.38 mm x 59.46 mm and 234 components. The input noise of the amplifier is approx. 546 pV/Hz with a noise figure (NF) of approx. 1.4 dB with a receive coil termination. Furthermore, a comparison between the prototyped LNA and a commercially available amplifier is shown.