Siemens Aktiengesellschaft

Other

Peter Schweighofer

Franz Schmitt

Michael Moritz

Helmut Lenz

Walter Beyerlein

Peter Tichy

Peter Havel

A magnetic stimulation apparatus for triggering action potentials, particularly in more deeply disposed, neuro-muscular tissue of a patient as well, has at least one stimulation coil that has terminals connected to the output of a current-generating unit offers greater degrees of freedom in the selection of the current pulse shapes because the current-generating unit provides current pulses generated in non-resonant fashion for the stimulation coil.

Magnetic stimulation device

A measuring device for measuring the intermediate circuit voltage of a gradient amplifier of a magnetic resonance imaging apparatus has a measuring circuit with a potential-dividing connection to a voltage indicator, the measuring circuit being connected in series with a discharging resistor of the intermediate circuit capacitance, and being driven from the discharging current via the discharging resistor.

Measuring device for measuring the intermediate circuit voltage of gradient amplifiers

In an analog-to-digital converter circuit and a control device for a gradient amplifier, an analog difference signal is determined from an analog input signal and an analog converter signal. An integrator and an analog-to-digital converter are provided in order to integrate and digitalize the analog difference signal before further evaluation, thereby achieving high precision, resolution and stability with little outlay.

Analog-to-digital converter circuit and control device for a gradient amplifier of a magnetic resonance imaging system

In a signaling connection having at least two electrical conductors which different connect components and/or subassemblies, a reliable signal transmission is insured by providing at least one additional electrical conductor, arranged such that voltages which are induced by magnetic interference fields are compensated, even given strong magnetic interference and independent of the arrangement of the electronic components or subassemblies.

Signal-transmitting connection with protection against magnetic field interference

In a circuit for supplying a load with a direct voltage, a diode is connected in a current path for supplying the load, a step-up converter is connected in the current paths parallel with the diode, and a control unit drives the step-up converter according to predetermined criteria in order to supply the load at least partially via the step-up converter. Such a circuit has advantageous power consumption characteristics. In comparison to conventional circuits that require an expensive filter, this circuit is more economical and/or has a smaller structural size.

Circuit for supplying a load with a direct voltage

A power amplifier having at least one switched output stage and a control unit for determining drive data for the at least one switched output stage, the control unit including an encoder for encoding the drive data in order to generate a data signal (DAT) according to a serial data transmission protocol, a data transmission link is provided for the transmission of the data signal, and a modulator is provided for generating switching signals for the switched output stage or stages dependent on the data signal. The structural outlay for the power amplifier thus is reduced, particularly in the case of a power amplifier having a number of output stages.

Power amplifier and method for the drive of a power amplifier

In a method for generating respective drive signals for four switch elements of a power output stage, a start signal and a stop signal are generated depending on an on-duration value first and second changeover signals are generated for driving each of two switch elements depending on the start and stop signals; and the drive signals are generated depending on the first and second changeover signals. A drive device and a power output stage are operated according to this method.

Method and device for generating drive signals for a power output stage,

A magnetic stimulation device has at least one stimulation coil, which is connected with its terminals to the output of at least one controllable electronic power converter and which has an inductance and current and voltage carrying capability, so that the stimulation pulses it generates permeate at least one volume on the order of magnitude of limbs, head or trunk of a patient. The controllable electronic power converter contains at least one activatable and deactivatable power semiconductor switch with short switching times. The electronic power converter is connected with its input to a voltage intermediate circuit. The voltage intermediate circuit and the controllable electronic power converter have a layout for high output voltages and currents, so that action potentials can be triggered even in deeper neuromuscular tissue of a patient, and the magnetic stimulation device offers wide freedom in the selection of the stimulation pulse shapes.

In a gradient amplifier for a nuclear magnetic resonance tomography apparatus and a method for operating same, a reference value unit for providing a reference value for a gradient coil current, an actual value unit for determining an actual value of the gradient coil current, a control unit for determining a setting value, a modulator for generating at least one output stage drive signal and an output stage for generating an output signal across the coil are provided. The precision of the reference value and the precision of the actual value are higher by at least the factor of 10 than the precision of the setting value and/or of the at least one output stage drive signal and/or of the output signal. As a result, the gradient amplifier has a precision that is high enough to avoid disturbances affecting in the image can be realized with relatively little outlay.

Gradient amplifier for a magnetic resonance tomography apparatus and

In a flexible and uncomplicated method for generating control signals for a power amplifier, and in a power amplifier having at least two output stages connected in series at the output side, which are driven dependent on a setting value, the setting value is classified into one of several setting value classes, a respective operating mode for each output stage is determined at least dependent on the setting value class and on a time slice value and at least one control signal for each output stage is generated dependent on the operating mode and, if warranted, on the setting value.

Method for the generation of control signals for a power amplifier and

A power amplifier has an amplifier assembly and a resonant assembly with a resonant capacitor and a control element. A parallel resonant circuit can be formed by the resonant capacitor and a load that can be connected to the amplifier. An output voltage or an intermediate circuit voltage of the amplifier can be applied at the resonance capacitor via the control element. An NMR tomography apparatus has at least one such power amplifier. The power amplifier can be universally used with low components outlay and is able to generate a number of signal forms.

Power amplifier for use in an NMR tomography apparatus

A power switched amplifier has a switched output stage which generates an output stage voltage and a filter stage coupled to the switched output stage for smoothing the output stage voltage. The smoothing effect of the filter stage is made to be variable with a control signal. Given little outlay, such an amplifier is capable of generating a well-smoothed output voltage with a high voltage change rate.

Power switched amplifer

In a power amplifier having multiple, switched output stages and a driver, and method for driving the switched output stages, a number of drive signal groups are generated for respectively driving the switched output stages. A number of pattern signal groups are generated dependent on at least one input signal, and drive signal groups are generated from the pattern signal groups, with each pattern signal group being allocated respectively to one of the switched output stages, and this allocation is changed in segments. A good load balancing between the individual switched output stages is achieved with a low circuit-oriented outlay.

Power amplifier with multiple, switched output stages, and method and

A drive arrangement for a switched output stage, such as an output stage of a gradient intensifier of a tomography apparatus has a pulse-width modulator and drive logic for producing at least two drive signals. The drive logic produces, for each drive signal, an edge of each on-phase pulse at a time made fixed corresponding to a time reference clock signal thereby allowing a fine adjustment of the on-phase of the power transistors of the switched output stage with low components costs, and a prescribed dead time between the individual on-phases is reliably adhered to.

Regulated inverter having a switched output stage and driver circuit

In a method for the drive of a number of coupled output stages drive signals for the output stages are generated. Given an over-voltage condition in one of the output stages, the output stage affected by the over-voltage condition is switched into a charge output mode for a limited time duration and at least one other output stage is switched into a charge pick-up mode for a limited time. This method is utilized in the operation of a control module and of a power amplifier, and achieves a charge compensation or balancing or equalization between the output stages with very little circuit-oriented outlay.

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Nuremberg, Germany

Peter Schweighofer