TRANSMIT/RECEIVE SWITCHING CIRCUITRY WITH IMPROVED RADIO FREQUENCY ISOLATION

摘要

A transmit/receive switching circuitry (40; 48) for a magnetic resonance radio frequency antenna (M) for use in an magnetic resonance imaging system (10), the transmit/receive switching circuitry comprising: -a radio frequency input transmission line (TX) provided for transmitting radio frequency power to the magnetic resonance radio frequency antenna (M) and a radio frequency output transmission line (RX) provided for transferring away magnetic resonance signals received by the magnetic resonance radio frequency antenna (M) at a magnetic resonance frequency from the magnetic resonance radio frequency antenna (M);—a parallel resonant circuit (42) with a resonance frequency that is substantially equal to the magnetic resonance frequency, and that is connected in parallel to the magnetic resonance radio frequency antenna (M) with regard to the radio frequency input transmission line (TX),—a series resonant circuit (44) with a resonance frequency that is substantially equal to the magnetic resonance frequency,and that is connected in series between the radio frequency input transmission line (TX) and the radio frequency output transmission line (RX); for providing improved radio frequency isolation between the radio frequency input transmission line (TX) and the radio frequency output transmission line (RX); a method for generating consecutive RF transmit periods and RF receive periods of the magnetic resonance imaging system (10) using such a transmit/receive switching circuitry (40; 48); a switching control unit (32) having at least one such transmit/receive switching circuitry (40; 48), for use in the magnetic resonance imaging system (10); a software module (26) for controlling an execution of such a method.

主权项

1. A T/R switching circuitry for a MR RF antenna for use in an MR imaging system, the T/R switching circuitry comprising:
an RF input transmission line provided for transmitting RF power to the MR RF antenna (M); an RF output transmission line provided for transferring MR signals away from the MR RF antenna, wherein the MR signals are to be received by the MR RF antenna at an MR frequency; at least two RF solid state switching members, wherein the RF input transmission line is connected to the MR RF antenna via a first one of the at least two RF solid switching members; a bias current generating circuit provided for generating DC bias current for the at least two RF solid state switching members; wherein an RF impedance of the at least two RF solid state switching members is controllable between a substantially electrically non-conducting state and a substantially electrically conducting state by variation of the bias current; at least a first inductor and at least a first capacitor that are connected via the first one of the at least two RF solid state switching members; wherein the first one of the at least two RF solid state switching members and one out of the first inductor and the first capacitor are connected in series between the RF input transmission line and the RF output transmission line; and wherein the first inductor and the first capacitor form a parallel resonant circuit with a resonance frequency that is substantially equal to the MR frequency, and that is connected in parallel to the MR RF antenna with regard to the RF input transmission line, when the at least two RF solid state switching members are in the substantially electrically conducting state; at least a second inductor that is connected in series between the one out of the first inductor and the first capacitor and the RF output transmission line, if the first capacitor is connected in series between the RF input transmission line and the RF output transmission line, or at least a second capacitor that is connected in series between the one out of the first inductor and the first capacitor and the RF output transmission line, if the first inductor is connected in series between the RF input transmission line and the RF output transmission line, wherein the second inductor and the first capacitor or the second capacitor and the first inductor form a series resonant circuit with a resonance frequency that is substantially equal to the MR frequency, and that is connected in series between the first one of the at least two RF solid state switching members and the RF output transmission line; and wherein the second one of the at least two RF solid state switching members is connected to the common node of the inductor and the capacitor of the series resonant circuit.