Frequency-Offset Cartesian Feedback for MRI Power Amplifier Linearization
نویسندگان
چکیده
منابع مشابه
Feedback for High-Bandwidth Power Amplifier Linearization
Current RF power amplifier (PA) linearization techniques are presently being investigated to improve PA linearity and power efficiency. One such linearization technique, Cartesian feedback (CFB), makes use of analog feedback to linearize a nonlinear plant (Figure 1). The commanded baseband symbol, I and Q, are compared to the symbol being transmitted by the PA, the baseband symbol is predistort...
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Introduction: We have previously proposed the use of Frequency-Offset Cartesian electronic feedback (FOCF) to deal with the rising challenges associated with control over the RF transmission fields in arrays of coils [1] [2]. In comparison to back-off, high transistor counts and other linearization methods, Cartesian feedback— like Vector Iterative Predistortion, VIP [3]—does not trade efficien...
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A phase-alignment system is used fully integrate a power amplifier, Cartesian feedback linearization circuitry, and a phasealignment system. The phase-alignment system employs a new technique for offset-free analog multiplication that enables it to function without manual trimming. This paper demonstrates how the phase-alignment system improves the stability margins of the fully integrated Cart...
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Introduction: Coupling between coil elements of a transmit array is one of the key challenges faced by designers of MRI transmitter arrays. To address this challenge, methods and systems have been developed to change the output impedance of the RF power amplifiers driving the array coils in order to suppress inter-element coupling effects. Chu [1], for example, proposed an output-matching netwo...
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Power amplifier linearization has become an important part of the transmitter system as 3G and developing 4G communication standards require higher linearity than ever before. The thesis proposes two power amplifier linearization solutions : two-point architecture and adaptive digital predistortion using a AE modulator for automatic inversion of power amplifier nonlinearity. Two-point architect...
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ژورنال
عنوان ژورنال: IEEE Transactions on Medical Imaging
سال: 2011
ISSN: 0278-0062,1558-254X
DOI: 10.1109/tmi.2010.2087768