Abstract:
An arrangement to transmit magnetic resonance signals has at least two reception branches. Each reception branch contains a single antenna of a local coil as well as an amplifier connected with the single antenna, such that an amplified magnetic resonance signal is formed from a magnetic resonance signal that is acquired via the single antenna. In a multiplexer, each input is connected with a respective reception branch, such that the amplified magnetic resonance signals of the reception branch are combined by the multiplexer into a resulting signal using a time multiplexing method. A transmission path is connected on one side with an output of the multiplexer and on the other side with a receiver, such that the resulting signal is transmitted from the multiplexer to the receiver via the transmission path.
Abstract:
An arrangement to transmit magnetic resonance signals has at least two reception branches. Each reception branch contains a single antenna of a local coil as well as an amplifier connected with the single antenna, such that an amplified magnetic resonance signal is formed from a magnetic resonance signal that is acquired via the single antenna. In a multiplexer, each input is connected with a respective reception branch, such that the amplified magnetic resonance signals of the reception branch are combined by the multiplexer into a resulting signal using a time multiplexing method. A transmission path is connected on one side with an output of the multiplexer and on the other side with a receiver, such that the resulting signal is transmitted from the multiplexer to the receiver via the transmission path.
Abstract:
In a mixer circuit with a balanced frequency mixer with varactor diodes, a first input signal that exhibits a first input frequency can be fed to the frequency mixer via a first input. Furthermore, a second input signal that exhibits a second input frequency can be fed to the frequency mixer via a second input. The frequency mixer has at least two amplifier elements fashioned as varactor diodes. These amplifier elements mix the input signals with one another into a mix signal with a first signal component and a second signal component. The first signal component exhibits a first component frequency, the second signal component a second component frequency. The first component frequency is equal to the sum of the first and second input frequencies, the second component frequency is equal to the difference of the first and second input frequencies. An output signal that contains at least one of the signal components can be tapped via the output. The frequency mixer is fashioned as a balanced frequency mixer in which at least the second input and the output are decoupled from one another. The second input frequency is a multiple of the first input frequency. An adjustment circuit for adjustment of an operating point of the varactor diodes is connected in parallel with each varactor diode.
Abstract:
Method for operating an RF power amplifier (100; 200) with an approximately linear characteristic by adjusting at least one operating parameter of the amplifier or at least one active component of this amplifier, wherein a minimum collector or drain current of the active component or, respectively, an amplifier stage and the input signal level of the RF power amplifier are controlled in dependence on the quotient of harmonic power and useful-signal power of the amplifier output signal.