56 research outputs found

    A Spectral-Scanning Magnetic Resonance Imaging (MRI) Integrated System

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    An integrated spectral-scanning magnetic resonance imaging (MRI) technique is implemented in a 0.12μm SiGe BiCMOS process. This system is designed for small-scale MRI applications with non-uniform and low magnetic fields. The system is capable of generating customized magnetic resonance (MR) excitation signals, and also recovering the MR response using a coherent direct conversion receiver. The operation frequency is tunable from DC to 37MHz for wide-band MRI and up to 250MHz for narrow-band MR spectroscopy

    A Spectral-Scanning Nuclear Magnetic Resonance Imaging (MRI) Transceiver

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    An integrated spectral-scanning nuclear magnetic resonance imaging (MRI) transceiver is implemented in a 0.12 mum SiGe BiCMOS process. The MRI transmitter and receiver circuitry is designed specifically for small-scale surface MRI diagnostics applications where creating low (below 1 T) and inhomogeneous magnetic field is more practical. The operation frequency for magnetic resonance detection and analysis is tunable from 1 kHz to 37 MHz, corresponding to 0-0.9 T magnetization for ^1H (hydrogen). The concurrent measurement bandwidth is approximately one frequency octave. The chip can also be used for conventional narrowband nuclear magnetic resonance (NMR) spectroscopy from 1 kHz up to 250 MHz. This integrated transceiver consists of both the magnetic resonance transmitter which generates the required excitation pulses for the magnetic dipole excitation, and the receiver which recovers the responses of the dipoles

    Near-Field Direct Antenna Modulation (NFDAM) transmitter at 2.4GHz

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    A near-field direct antenna modulation (NFDAM) transmitter at 2.4GHz is demonstrated on a microstrip setting. The transmitter is capable of transmitting information in a direction-dependent fashion by sending the correct signal constellation only in the desired direction while leaving the signal constellation points scrambled in undesired directions. This direction-dependent constellation scrambling nature of the NFDAM systems prevents undesired receivers to correctly demodulate the signal transmitted to a desired receiver at a specific direction

    Near-field direct antenna modulation

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    NFDAM systems provide a unique solution for transmitting highly secured direction-dependent data and hence preventing eavesdroppers from properly demodulating the signal. A 60-GHz proof-of-concept chip was designed and measured

    Transmitter Architectures Based on Near-Field Direct Antenna Modulation

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    A near-field direct antenna modulation (NFDAM) technique is introduced, where the radiated far-field signal is modulated by time-varying changes in the antenna near-field electromagnetic (EM) boundary conditions. This enables the transmitter to send data in a direction-dependent fashion producing a secure communication link. Near-field direct antenna modulation (NFDAM) can be performed by using either switches or varactors. Two fully-integrated proof-of-concept NFDAM transmitters operating at 60 GHz using switches and varactors are demonstrated in silicon proving the feasibility of this approach

    An Integrated Subharmonic Coupled-Oscillator Scheme for a 60-GHz Phased-Array Transmitter

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    This paper describes the design of an integrated coupled-oscillator array in SiGe for millimeter-wave applications. The design focuses on a scalable radio architecture where multiple dies are tiled to form larger arrays. A 2 × 2 oscillator array for a 60-GHz transmitter is fabricated with integrated power amplifiers and on-chip antennas. To lock between multiple dies, an injection-locking scheme appropriate for wire-bond interconnects is described. The 2 × 2 array demonstrates a 200–MHz locking range and 1 × 4 array formed by two adjacent chips has a 60-MHz locking range. The phase noise of the coupled oscillators is below 100 dBc/Hz at a 1-MHz offset when locked to an external reference. To the best of the authors’ knowledge, this is the highest frequency demonstration of coupled oscillators fabricated in a conventional silicon integrated-circuit process

    A 6-to-18 GHz tunable concurrent dual-band receiver front end for scalable phased arrays in 130nm CMOS

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    This paper presents a study and design of tunable concurrent dual-band receiver. Different system architectures and building blocks have been compared and analyzed. A tunable concurrent dual-band receiver front end has then been fabricated and characterized. It operates across a tri-tave 6-18 GHz bandwidth with a nominal 17-25 dB conversion gain, worst-case -15 dBm IIP3, and worst-case -24.5 dBm ICP 1 dB

    A 77-GHz Phased-Array Transceiver With On-Chip Antennas in Silicon: Receiver and Antennas

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    In this paper, we present the receiver and the on-chip antenna sections of a fully integrated 77-GHz four-element phased-array transceiver with on-chip antennas in silicon. The receiver section of the chip includes the complete down-conversion path comprising low-noise amplifier (LNA), frequency synthesizer, phase rotators, combining amplifiers, and on-chip dipole antennas. The signal combining is performed using a novel distributed active combining amplifier at an IF of 26 GHz. In the LO path, the output of the 52-GHz VCO is routed to different elements and can be phase shifted locally by the phase rotators. A silicon lens on the backside is used to reduce the loss due to the surface-wave power of the silicon substrate. Our measurements show a single-element LNA gain of 23 dB and a noise figure of 6.0 dB. Each of the four receive paths has a gain of 37 dB and a noise figure of 8.0 dB. Each on-chip antenna has a gain of +2 dBi

    A Near-Field Modulation Technique Using Antenna Reflector Switching

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    This paper presents a near-field reflector switching technique that can generate independently controlled modulated signals for sufficiently different angles of radiation. This technique can be used either to transmit different data in different directions simultaneously, or to generate the correct signal constellation only in the desired direction and scrambled ones for other angles, creating a secure communication link. This approach is also conducive to power-efficient switching PAs, even for wideband non-constant envelope modulation schemes, enabling fast and power-efficient transmitter architectures
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