Abstract:
An amplifier device including at least one operational amplifier, whereby a transformer is connected upstream from the input of the operational amplifier and the output signal of the operational amplifier or a signal generated from this output signal is fed back again to the input of the operational amplifier via a path with a predetermined resistance whereby the feedback signal is fed back before the input of the transformer whereby the transformer is designed or connected in a signal-inverting manner.
Abstract:
A method for determining positron emission measurement information in the context of positron emission tomography is disclosed. The method includes using a marker substance to carry out a positron emission measurement, in a body area of a subject to be examined, to determine positron emission measurement information, and at the same time, generating images of the body area to be examined by way of a second medical method with a time resolution suitable for determining perfusion and/or diffusion information. The method further includes using the images from the second method to determine perfusion and/or diffusion information for at least a part of the measurement period, and evaluating the positron emission measurement information as a function of the perfusion and/or diffusion information.
Abstract:
A controller for an RF amplifier, in particular for a RF amplifier of an MR tomography apparatus, has an IQ control element for adjusting the magnitude and phase an RF signal that is be fed to the RF amplifier. The IQ control element has a signal splitter that splits the RF signal into two partial signals having a 90° phase offset in an I path and a Q path, each having a multiplier for multiplying the partial signal by an I factor in the I path and a Q factor in the Q path. A summing unit recombines the partial signals. A detector determines the actual phase difference and actual amplification between the RF signal fed to the IQ control element and the RF signal amplified by the RF amplifier. An IQ controller determines the I factor and the Q factor from the actual difference and a desired phase difference and the actual amplifier and a desired amplification. The IQ controller has an operating point at which the I factor and the Q factor are the same magnitude if the actual and desired phase differences and the actual and desired amplifications are the same.
Abstract:
A reception unit for a magnetic resonance tomography apparatus has an RF preamplifier connected at its signal input to a local coil with a PIN diode connected in parallel with the signal input and a supply voltage connection of the RF preamplifier being connected to a direct voltage source. The reception unit has a supply node that is connected with the supply voltage connection, the PIN diode and a cross-over switch for alternating connection of the supply node to the direct voltage source or a direct current source.
Abstract:
A crossbar switch comprises a number of crossing points at which controllable switch elements are arranged, via which an input signal supplied to a row can be interconnected to a column intersecting this row at this crossing point when an interconnection signal is supplied to the respective setting parameter via a control input. The controllable switch elements comprise amplifier elements whose amplifier inputs are connected with the rows and whose amplifier outputs are connected with the columns. The amplifier elements are wired such that they only consume electrical energy when the interconnection signal is supplied to the respective crossing point.
Abstract:
A controllable two-phase network for production of two output signals at two loads with identical load impedances from an input signal from a source containing a phase path for production of a first output signal, and an amplitude path for production of a second output signal, from the input signal. The phase path contains a trimming resistance and a trimming capacitance in order to influence the phase shift between the input signal and the first output signal. The amplitude path contains a compensation circuit for matching the amplitude of the second output signal to the amplitude of the first output signal. In particular, the two-phase network is designed such that the two output signals have the same amplitude, and the phase of the first output signal has a constant phase shift with respect to that of the second output signal.
Abstract:
In a magnetic resonance system and an operating method therefor, a B1 field distribution of a radio-frequency antenna is measured in at least one part of a examination volume of the magnetic resonance system, and then the RF pulses emitted by the radio-frequency antenna are optimized, based on the determined B1 field distribution, for homogenization in a specific volume. An effective volume within the examination volume is determined beforehand for each applied RF pulse and, based on the determined B1 field distribution, the appertaining RF pulse is individually adjusted such that the B1 field is homogenized within the effective volume of the RF pulse.
Abstract:
Circuit arrangement for the switchable amplification of variable electrical signals having at least one signal input and a signal output. A switchable amplifier is present between signal input and signal output and is provided with an input, with an output and with a negative feedback path having at least one resistor between input and output. The circuit arrangement further comprises a voltage source, the polarity of which can be reversed by a switching element. In this case, the negative feedback path has a switchable bypass connected in parallel with the at least one resistor. The signals fed in at the amplifier input are furthermore to be fed to the amplifier output in amplified fashion via a first signal path or in unamplified fashion via a second signal path depending on the polarity of the voltage source.
Abstract:
A crossbar switch comprises a number of crossing points at which controllable switch elements are arranged, via which an input signal supplied to a row can be interconnected to a column intersecting this row at this crossing point when an interconnection signal is supplied to the respective setting parameter via a control input. The controllable switch elements comprise amplifier elements whose amplifier inputs are connected with the rows and whose amplifier outputs are connected with the columns. The amplifier elements are wired such that they only consume electrical energy when the interconnection signal is supplied to the respective crossing point.
Abstract:
The invention relates to a method and a device for taking an image 2 of an object surface 1 by means of a focusable radiation 3. An array of object elements 4 that covers the object surface is defined; then, for each object element 1, a first signal of the radiation that is focused onto an associated transmitter line 5, including said object element, in the object surface is emitted, and a second signal of the radiation that is generated by means of said first signal and is focused onto an associated receiver line 6, including the object element and crossing said transmitter line, in the object surface is received and an associated image information item is picked up therefrom; finally, the image is composed from the image information items of all the object elements.