Abstract: A radio frequency amplifier system for a magnetic resonance imaging (MRI) apparatus has a radio frequency power amplifier configured to transmit a B1 radiofrequency signal to a patient coil present in the MRI apparatus and a first directional coupler that splits the B1 signal from the amplifier into a transmitted B1 signal and a B1 error signal. A circulator transmits the transmitted B1 signal to a patient coil, and receives and transmits a reflected B1 signal and an MRI signal from the patient coil. The signals received from the patient coil are fed to a control loop. The components of the control loop modify the B1 error signal so that the B1 error signal cancels the B1 reflected signal such that the transmitted signal consists only of the MRI signal without a B1 signal, which is then sent to a low noise MRI signal amplifier and on for diagnostic analysis.

Abstract: A radio frequency amplifier system for a magnetic resonance imaging (MRI) apparatus has a radio frequency power amplifier configured to transmit a B1 radiofrequency signal to a patient coil present in the MRI apparatus and a first directional coupler that splits the B1 signal from the amplifier into a transmitted B1 signal and a B1 error signal. A circulator transmits the transmitted B1 signal to a patient coil, and receives and transmits a reflected B1 signal and an MRI signal from the patient coil. The signals received from the patient coil are fed to a control loop. The components of the control loop modify the B1 error signal so that the B1 error signal cancels the B1 reflected signal such that the transmitted signal consists only of the MRI signal without a B1 signal, which is then sent to a low noise MRI signal amplifier and on for diagnostic analysis.