Design of a 5 T Non-magnetic Magnetic Resonance Radio Frequency Power Amplifier

Abstract

This paper introduces the design and implementation of a 5 T magnetic resonance radio frequency power amplifier (RFPA), which can be used in scan rooms without a circulator. The RFPA was designed based on laterally-diffused metal-oxide semiconductor (LDMOS) power tube with high standing wave tolerance, and it contained a three-stage amplifier circuit. The transmission line transformers with magnetic core in RFPA was designed as non-magnetic. The reflected power was monitored tensely. The nonlinear automatic correction of RFPA was realized by using analogic negative feedback technology. The results showed that the output of RFPA power is up to 2 kW, the gain linearity performance is less than or equal to 1 dB, and the phase linearity performance is less than or equal to 10 deg over 40 dB range up to rated power during the load disturbance (reflection coefficient Г < 0.5), which meets the imaging requirements. Thus the rationality and feasibility of the proposed design scheme are verified.

Keywords

• magnetic resonance imaging (mri)
• power amplifier
• non-magnetic
• negative feedback