High-frequency interface circuit, high-frequency system and magnet resonance apparatus with a high-frequency interface circuit

1. A high-frequency (HF) interface circuit comprising:

a connector (PR) that links to a HF arrangement,

a transmit path (SP) which links an input (TX) of the high-frequency interface circuit to the connector (PR), wherein the input (TX) receives signals transmitted by a HF generator;

a receive path (EP) that links the connector (PR) to an output (RX) of the high-frequency interface circuit, whereby the receive path (EP) includes a first circuit (K 1 ) and wherein the output (RX) directs signals to a receiver system,

whereby the first circuit (K 1 ) includes at least a first switching element (S 1 ) that is electro-conductive in transmit mode and electrically insulating in receive mode,

whereby, in the transmit mode, the first circuit (K 1 ) forms first and second parallel resonance circuits connected in series that isolate the output (RX) of the high-frequency interface circuit from the connector (PR);

wherein in the receive mode, the first circuit (K 1 ) includes first and second series resonance circuits connected in parallel

wherein the receive path (EP) further includes a second grounding switching element (S 2 ) that is electro-conductive in the transmit mode and electrically insulating in the receive mode.

2. The high-frequency interface circuit as claimed in claim 1 , wherein

the first circuit (K 1 ) comprises a first inductive element (L 1 ), a second inductive element (L 2 ), a first capacitive element (C 1 ) and a second capacitive element (C 2 ),

in the transmit mode, the second capacitive element (C 2 ) together with the first inductive element (L 1 ) and the first capacitive element (C 1 ) together with the second inductive element (L 2 ) form, respectively, the first and the second parallel resonance circuits of the first circuit (K 1 ) and

the first switching element (S 1 ) is part of both the first and the second parallel resonance circuits, and

in the receive mode, the second capacitive element (C 2 ) together with the second inductive element (L 2 ) and the first capacitive element (C 1 ) together with the first inductive element (L 1 ) form, respectively, the first and the second series resonance circuits of the first circuit (K 1 ).

3. The high-frequency interface circuit as claimed claim 1 , wherein the second switching element (S 2 ) in the receive path (EP) is positioned directly before the output (RX) of the high-frequency interface circuit.

4. The high-frequency interface circuit as claimed in claim 1 , wherein the transmit path (SP) includes an input-isolator circuit with a fourth switching element (S 4 ) that is electro-conductive in the transmit mode and electrically insulating in the receive mode.

5. The high-frequency interface circuit as claimed in claim 4 , wherein the input-isolator circuit is a HF filter in the transmit mode.

6. A high-frequency system with a HF generator generating HF signals, a HF arrangement that is configured to send and detect HF signals, a receiver system that is configured to process the detected HF signals and a high-frequency interface circuit as claimed in claim 1 , whereby the HF generator is connected to the input (TX) of the high-frequency interface circuit, the receiver system is connected to the output (RX), and the HF arrangement is connected to the connector (PR) of the high-frequency interface circuit.

7. A magnetic resonance apparatus with a HF arrangement that excites magnetic resonances and receives MR signals and with the high-frequency interface circuit as claimed in claim 1 .

8. The magnetic resonance apparatus as claimed in claim 7 , wherein the HF arrangement is an MR probe.

9. The use of the high-frequency interface circuit as claimed in claim 1 in a magnetic resonance apparatus that performs multi-resonance MR measurements.

10. The high-frequency interface circuit as claimed in claim 3 , wherein the receive path (EP) includes a second circuit (K 2 ) that is connected to the first circuit (K 1 ) in series, whereby the second switching element (S 2 ) is part of the second circuit (K 2 ), and whereby the second circuit (K 2 ) forms a low pass filter in the receive mode and a third parallel resonance circuit in the transmit mode.

11. The high-frequency interface circuit as claimed in claim 1 , wherein the interface circuit is in the transmit mode when the first switching element (S 1 ) is closed, and wherein the interface circuit is in the receive mode when the first switching element (S 1 ) is open.

12. A high-frequency (HF) interface circuit to direct signals transmitted by a HF generator to a connector (PR) for a HF arrangement in a transmit mode via an input (TX) of the high-frequency interface circuit and to direct received signals from the connector (PR) of the HF arrangement to a receiver system in a receive mode via an output (RX) of the high-frequency interface circuit, whereby the interface circuit comprises:

a transmit path (SP) which links the input (TX) of the high-frequency interface circuit to the connector (PR);

a receive path (EP) that links the connector (PR) to the output (RX) of the high-frequency interface circuit, whereby the receive path (EP) includes a first circuit (K 1 ), wherein the first circuit (K 1 ) comprises a first inductive element (L 1 ), a second inductive element (L 2 ), a first capacitive element (C 1 ), and a second capacitive element (C 2 ),

whereby the first circuit (K 1 ) includes at least a first switching element (S 1 ) that is electro-conductive in the transmit mode and electrically insulating in the receive mode, such that the first switching element (S 1 ) is part of both first and second parallel resonance circuits of the first circuit (K 1 ),

whereby, in the transmit mode, the first circuit (K 1 ) forms the first and the second parallel resonance circuits connected in series that isolate the output (RX) of the high-frequency interface circuit from the connector (PR), wherein the second capacitive element (C 2 ) together with the first inductive element (L 1 ) and the first capacitive element (C 1 ) together with the second inductive element (L 2 ) form, respectively, the first and the second parallel resonance circuits of the first circuit (K 1 ), and

wherein

in the receive mode, the first circuit (K 1 ) includes the first and the second series resonance circuits connected in parallel, wherein the second capacitive element (C 2 ) together with the second inductive element (L 2 ) and the first capacitive element (C 1 ) together with the first inductive element (L 1 ) form, respectively, the first and the second series resonance circuits of the first circuit (K 1 ), and

wherein the receive path (EP) includes a second grounding switching element (S 2 ) that is electro-conductive in the transmit mode and electrically insulating in the receive mode, and

wherein the receive path (EP) includes a second circuit (K 2 ) that is connected to the first circuit (K 1 ) in series, whereby the second switching element (S 2 ) is part of the second circuit (K 2 ), and whereby the second circuit (K 2 ) forms a low pass filter in the receive mode and a third parallel resonance circuit in the transmit mode.

13. The high-frequency interface circuit as claimed in claim 12 , wherein the second circuit (K 2 ) includes a third inductive element (L 3 ) and a third capacitive element (C 3 ) that together form part of the third parallel resonance circuit in the transmit mode and part of the low pass filter in the receive mode.

14. The high-frequency interface circuit as claimed in claim 12 , wherein the second circuit (K 2 ) additionally includes a fourth capacitive element (C 4 ) and a third grounding switching element (S 3 ) that is electro-conductive in the transmit mode and electrically insulating in the receive mode, whereby, in the transmit mode, the fourth capacitive element (C 4 ) is part of the third parallel resonance circuit.

15. The high-frequency interface circuit as claimed in claim 12 , wherein the second circuit (K 2 ) additionally includes a fifth capacitive element (C 5 ) that is located parallel to the second switching element (S 2 ) and is part of the low pass filter in the receive mode.

16. The high-frequency interface circuit as claimed in claim 13 , wherein the inductance of the third inductive element (L 3 ) is half as big as the inductance of the first inductive element (L 1 ) or the second inductive element (L 2 ).

17. The high-frequency interface circuit as claimed in claim 13 , wherein the second circuit (K 2 ) additionally includes a fourth capacitive element (C 4 ) and a third grounding switching element (S 3 ) that is electro-conductive in the transmit mode and electrically insulating in the receive mode, whereby, in the transmit mode, the fourth capacitive element (C 4 ) is part of the third parallel resonance circuit.

18. The high-frequency interface circuit as claimed in claim 13 , wherein the second circuit (K 2 ) additionally includes a fifth capacitive element (C 5 ) that is located parallel to the second switching element (S 2 ) and is part of the low pass filter in the receive mode.

19. The high-frequency interface circuit as claimed in claim 14 , wherein the second circuit (K 2 ) additionally includes a fifth capacitive element (C 5 ) that is located parallel to the second switching element (S 2 ) and is part of the low pass filter in the receive mode.

20. The high-frequency interface circuit as claimed in claim 14 , wherein the inductance of the third inductive element (L 3 ) is half as big as the inductance of the first inductive element (L 1 ) or the second inductive element (L 2 ).

21. The high-frequency interface circuit as claimed in claim 15 , wherein the inductance of the third inductive element (L 3 ) is half as big as the inductance of the first inductive element (L 1 ) or the second inductive element (L 2 ).