Small footprint high gain and low noise figure preamplifier for 7T MRI scanner

This work presents the design and construction of a low input impedance preamplifier with a gain of more than 30 dB and a noise figure of less than 1 dB. It has a low input impedance, around 1Ω. A λ/4 transmission line is used to transform the low input impedance of the preamplifier to a high impedance at the coil to reduce the cross-coupling between coils. In order to test the preamplifier, a single-transmit, single-receive coil was developed at 297.2 MHz. The designed preamplifier can have a footprint as small as 27 mm × 13 mm. Small footprint preamplifiers are crucial where space is at a premium in multichannel coil arrays.