In MRI system, considerable signal loss exists in the long coaxial cable and RF circuits of a transceiver module. In other words, signal-to-noise ratio (SNR) becomes worse as the distance from the RF receiver coil increases. Thus, if a low-noise amplifier is placed near the receive RF coil, it amplifies the signal before the noise is added by the transmission line and the coupler circuits. The proposed circuit has two pathways with switching modules for signal transmission, so that the high power RF can be transmitted to the RF coil and the low energy RF signal from the RF coil can be amplified by a low-noise amplifier. The proposed circuit provides with signal isolation as high as possible for protection of the pre-amplifier from the high power.
