title: A high-field magnetic resonance imaging spectrometer using an oven-controlled crystal oscillator as the local oscillator of its radio frequency transceiver.
abstract: A home-made high-field magnetic resonance imaging (MRI) spectrometer with multiple receiving channels is described. The radio frequency (RF) transceiver of the spectrometer consists of digital intermediate frequency (IF) circuits and corresponding mixing circuits. A direct digital synthesis device is employed to generate the IF pulse; the IF signal from a down-conversion circuit is sampled and followed by digital quadrature detection. Both the IF generation and the IF sampling use a 50 MHz clock. An oven-controlled crystal oscillator, which has outstanding spectral purity and a compact circuit, is used as the local oscillator of the RF transceiver. A digital signal processor works as the pulse programmer of the spectrometer, as a result, 32 control lines can be generated simultaneously while an event is triggered. Field programmable gate array devices are utilized as the auxiliary controllers of the IF generation, IF receiving, and gradient control. High performance, including 1 μs time resolution of the soft pulse, 1 MHz receiving bandwidth, and 1 μs time resolution of the gradient waveform, is achieved. High-quality images on a 1.5 T MRI system using the spectrometer are obtained.
authors.affiliation: Department of Information Engineering, College of Information Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Liang
authors.affiliation: Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Tang
authors.affiliation: Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
authors.forename: Weinan
authors.initials: W
authors.lastname: Tang
authors.affiliation: Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Gao
mesh_terms: D001921:Brain; D004867:Equipment Design; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D011846:Radio Waves