Multiturn MRI Coils In Combination With Current Mode Class D Amplifiers

An apparatus, comprising:

• a multi-turn transmit surface coil configured for high field parallel magnetic resonance imaging (MRI), the multi-turn transmit surface coil being configured to be driven by:
• a high frequency radio frequency (RF) signal generator to generate an RF signal at a high frequency of at least 250 MHz;
• a balun network that inputs the RF signal with respect to ground and converts the input RF signal into a pair of first and second balanced out-of-phase signals with respect to ground at the high frequency;
• and
• a push-pull amplifier comprising a first field effect transistor (FET) driven by the first out-of-phase signal and a second FET driven by the second out-of-phase signal, the first and second FETs being connected in a push pull configuration;
• where the first and second FETs switch an on-coil current-mode class-D (CMCD) amplifier that includes two CMCD FETs that drive an inductance-capacitance (L-C) leg to control production of an RF signal at the high frequency by the multi-turn transmit surface coil.

An MRI apparatus, comprising:

• a transmit surface coil configured with two or more turns;
• and
• a control apparatus comprising:
• a high frequency radio frequency (RF) signal generator to generate an RF signal at a high frequency of at least 300 MHz;
• a balun network electrically connected to the RF signal generator to output a pair of first and second balanced out-of-phase signals at the high frequency;
• and
• a push-pull amplifier comprising a first field effect transistor (FET) driven by the first out-of-phase signal and a second FET driven by the second out-of-phase signal, the first and second FETs being connected in a push pull configuration;
• where an L-C-switched-mode coil is controlled by an output of the push pull amplifier to output an analog RF signal at the desired frequency,
• where transmissions from the transmit surface coil are controlled by the control apparatus.

A method, comprising:

• receiving an RF signal having a high frequency of at least 300 MHz;
• generating an opposite phase signal comprising first and second out-of-phase signals by passing the RF signal through a balun network;
• amplifying the first and second out-of-phase signals with a push-pull amplifier;
• and
• providing the amplified out-of-phase signals to CMCD FETs in an on-coil CMCD amplifier that drives an L-C leg to excite an MRI transmit coil to transmit an RF signal, the MRI transmit coil having two or more turns.