Koninklijke Philips Corporation N.V.

U.S. Philips Corporation

Koninklikje Philips N.v.

Koninklijke Philips Electronics N.v.

Eerke Holle

Evert Seevinck

Marinus Johannes Adrianus Maria Van Helvoort

Robert Paul Kleihorst

Marinus J A M Van Helvoort

Roelof F Wassenaar

Paulus C H A Haans

Andreas Henricus Wilhelmus Snelders

Cornelis Wilhelmus Jacobs

Math Rietjens

Cornelis W Jacobs

A magnetic resonance radio frequency transmission device () for generating and applying a radio frequency excitation field Bfor the purpose of magnetic resonance examination comprises a birdcage coil () and a plurality of M radio frequency amplifier units for providing radio frequency power at a magnetic resonance frequency to the birdcage coil () via a plurality of M activation ports () selected out of the plurality of N activation ports (). In an operational state of the birdcage coil () each radio frequency amplifier unit () is electrically connected and is arranged in close proximity to an activation port (). Among the plurality of M radio frequency amplifier units (), there is established a fixed relationship of adjustable phase angles (&#x3c6;) of the magnetic resonance radio frequency power provided by the plurality of M radio frequency amplifier units (); a method of generating and applying a radio frequency excitation field B for the purpose of magnetic resonance examination, using such magnetic resonance radio frequency transmission device (); and a magnetic resonance imaging system () configured for acquiring magnetic resonance images of at least a portion of a subject of interest (), comprising such magnetic resonance radio frequency transmission device ().

MRI birdcage coil with distributed excitation

A radio frequency coil for transmitting or receiving signals at a magnetic resonance frequency includes an arrangement of substantially parallel rungs () and one or more generally annular strip-type end-rings () disposed generally transverse to the parallel rungs and connected with the rungs. Each generally annular strip-type end-ring includes at least two conductor layers () separated by a dielectric layer (). A radio frequency shield () substantially surrounds the arrangement of substantially parallel rungs (). At least one of the conductor layers of each end-ring is connected with the radio frequency shield.

Radio frequency coil with transmission line end-rings

A combiner/splitter device () comprises two transmission lines (), wound to form a helical coil (), this helical coil being bent to a toroidal shape. Furthermore, a capacitor () is provided, connected in parallel with the two outer conductors () of the two transmission lines (). The combination of the wound transmission lines and said capacitor forms a parallel resonator (). The combiner/splitter device is suitable for use in a magnetic resonance imaging (MRI) system to combine the output signals of a receiver coil system and/or to split the input signal of a transmission coil system used in the MRI system.

Combiner/splitter device for an MRI system

A radio-frequency coil (RF-coil) () for use in a magnetic-resonance imaging apparatus comprises a number of parallel bar-shaped electric conductors () arranged at regular intervals on an imaginary cylinder () and surrounded by a radio-frequency shield (RF-shield) (). The bar-shaped conductors surround a measuring volume () and are interconnected at least at one of their end portions () by an electric end conductor () extending in a plane transverse to the bar-shaped conductors. A further electric end conductor () is arranged near and parallel to the end conductor (), and is electrically connected to the RF-shield (), preferably by a flange-shaped electric conductor (). The end conductor () and the further end conductor () together form a transmission line. An unwanted electromagnetic field (b) generated by current in the end conductor () is compensated for by an electromagnetic field (b) generated by the current in the further end conductor (). Thus, the electromagnetic field of the end conductor () does not lead to unwanted dissipation effects and temperature increases in the body of a patient present in the measuring volume ().

Radio frequency coil with two parallel end conductors

The invention relates to a resonance trap ( ) for suppressing electromagnetic coupling phenomena for a line ( ), which resonance trap includes a conductor ( ) which extends parallel to and along a part of the length of the line ( ). Conventional resonance traps ( ) have the drawback that a direct connection exists between the RF line and the individual resonance traps ( ). It is an object of the invention to provide a resonance trap ( ) which enables a modular assembly on the line ( ). The object is achieved by means of a resonance trap ( ) of the kind set forth in which inner conductors ( ) extend parallel to the line ( ) and in which outer conductors ( ) extend parallel to the inner conductors ( ), said inner conductors ( ) being arranged at a radial distance from the line ( ) which is smaller than that at which the outer conductors ( ) are arranged and the outer conductors ( ) being arranged to cover at least partly the inner conductors ( ) in the radial direction relative to the line ( ). This offers the advantage that the connection between the resonance trap ( ) and the line ( ) is dispensed with.

Device for suppressing electromagnetic coupling phenomena

An integrated circuit comprising a cascode current mirror and a bias stage for biassing the cascode current mirror, the cascode current mirror comprising, between an input terminal (11) and a supply voltage terminal (14), a first cascoded MOS transistor (21) and a first cascode MOS transistor (22) and, between an output terminal (12) and the supply voltage terminal (14), a second cascoded MOS transistor (23) and a second cascode MOS transistor (24). In order to obtain a minimal voltage between the output terminal (12) and the supply voltage terminal (14) the bias stage comprises a first bias current source (31) for generating a first bias current, a second bias current source (32) for generating a second bias current, a first bias MOS transistor (41) having a gate coupled to the gates of the two cascoded MOS transistors (21, 23), a source, and a drain coupled to the first supply voltage terminal (13) via the first bias current source (31), a second bias MOS transistor (42) having a gate coupled to the gates of the two cascode MOS transistors (22, 24), a source coupled to the source of the first bias MOS transistor (41), and a drain coupled to the first supply voltage terminal (13) via the second bias current source (32), and a third bias MOS transistor (43) coupled between the sources of the two bias MOS transistors (41, 42) and the second supply voltage terminal (14).

Integrated circuit having a cascode current mirror

A relates to a band-gap reference-voltage arrangement includes a MOS differential amplifier (OA2) having two inputs and one output. A first bipolar transistor (Q3) has its base/emitter path coupled between one input of the differential amplifier and a specific junction point and has an emitter-collector path arranged in a first current path for carrying a first current. A second bipolar transistor (Q4) has its base/emitter path connected in series with a resistor (R6) between the other input of the differential amplifier and said junction point and has its emitter-collector path arranged in a second current path for carrying a second current. First and second transistors (P1), P2) supply said first and second currents to the first and second current paths. A feedback path is provided for feeding back the signal from the output of the differential amplifier to the first junction point and comprises a third transistor (Q5) whose base-emitter path is connected between said junction point and the output of the differential amplifier.

Band-gap reference voltage circuit with feedback to reduce common mode

A voltage-current converter includes a first current-source (I.sub.1) coupled by means of a diode-arranged first transistor (T.sub.1) to a first terminal (1) at reference potential and by means of a diode-arranged second transistor (T.sub.2) to a second terminal (2). The bases of a third (T.sub.3) and a fourth (T.sub.4) transistor are coupled to the first (1) and the second (2) terminal, respectively. The emitters of these transistors (T.sub.3,T.sub.4) are coupled to a second current source (I.sub.2). A voltage source (V) and a resistor (R.sub.1) for converting the voltage (V) into a signal current are arranged between the first (1) and the second (2) terminal. The signal current is amplified by the translinear-circuit of the first, second, third and fourth transistors (T.sub.1 -T.sub.4) and fed to the outputs (30,40) via cascode transistors (T.sub.9,T.sub.10). To correct the non-linearity in the voltage-current conversion due to the non-linear emitter resistors of the first (T.sub.1) and the second (T.sub.2) transistor, a correction circuit (5) having a negative input resistance is coupled to the first (1) and the second (2) terminal.

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Eindhoven, Netherlands

Eerke Holle