Browsing by Author "Chen, Charles"
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Item Electron spin resonance for medical imaging(2018-01-02) Yang, Xuebei; Chen, Charles; Seifi, Payam; Babakhani, Aydin; Rice University; United States Patent and Trademark OfficeA method includes generating, from an integrated oscillator circuit, an oscillating output signal and generating, by an integrated power amplifier (PA) circuit, an amplified oscillating output signal based on the oscillating output signal. The method further includes receiving, by integrated receiver amplifier circuit, an electron spin resonance (ESR) signal from biological samples that include a magnetic species and generating, by the integrated receiver amplifier circuit, an amplified ESR signal based on the received ESR signal. The method further includes receiving, by the integrated receiver amplifier circuit, an electron spin resonance (ESR) signal from magnetic nanoparticles that are loaded with drugs or attached to human cells.Item Intergrated electron spin resonance spectrometer(2017-06-27) Yang, Xuebei; Chen, Charles; Seifi, Payam; Babakhani, Aydin; Rice University; United States Patent and Trademark OfficeAn integrated electron spin resonance (ESR) circuit chip includes a chip substrate, a transmitter circuit, and a receiver circuit. The transmitter circuit and receiver circuit are disposed on the chip substrate. The transmitter circuit includes an oscillator circuit configured to generate an oscillating output signal and a power amplifier (PA) circuit configured to generate an amplified oscillating output signal based on the oscillating output signal. The receiver circuit receives an ESR signal from an ESR probe. The receiver circuit includes a receiver amplifier circuit configured to generate an amplified ESR signal based on the received ESR signal, a mixer circuit configured to receive the amplified ESR signal and to down-convert the amplified ESR signal to a baseband signal, and a baseband amplifier circuit configured to generate an amplified baseband signal based on the baseband signal. An integrated electron spin resonance (ESR) circuit chip includes a chip substrate, a transmitter circuit, and a receiver circuit. The transmitter circuit and receiver circuit are disposed on the chip substrate. The transmitter circuit includes an oscillator circuit configured to generate an oscillating output signal and a power amplifier (PA) circuit configured to generate an amplified oscillating output signal based on the oscillating output signal. The receiver circuit receives an ESR signal from an ESR probe. The receiver circuit includes a receiver amplifier circuit configured to generate an amplified ESR signal based on the received ESR signal, a mixer circuit configured to receive the amplified ESR signal and to down-convert the amplified ESR signal to a baseband signal, and a baseband amplifier circuit configured to generate an amplified baseband signal based on the baseband signal.Item Wireless Synchronization and Spatial Combining of Widely-spaced mm-wave Arrays in Silicon(2017-07-26) Chen, Charles; Babakhani, AydinDue to the rapid advancement of semiconductor processes and the maturity of sub-5GHz RF design, there has been increasing interest in the higher-frequency, mm-wave (30GHz to 300GHz) and THz (300GHz to 3THz) regime. The higher carrier frequency enables exciting new applications such as radar, mm-wave imaging and spectroscopy. The main challenges at these frequencies include miniaturization, power generation and beamforming. Miniaturization allows for low-cost and accessible sensing applications. Higher power extends the detectable distance while a narrow beamwidth improves the angular resolution in radar imaging systems. In this thesis, we take various approaches to address these challenges. First, we present a fully-integrated transceiver for time-domain electron paramagnetic resonance (EPR) spectroscopy implemented using a 0.13μm SiGe BiCMOS technology. The system utilizes an on-chip resonator to study time domain relaxation behavior of paramagnetic samples, i.e. materials with unpaired electron spins. The single-chip EPR spectrometer consists of an EPR resonator, 22-26GHz tunable VCO, a programmable pulse generation block, RF buffer and power amplifier, a multi-stage LNA, and down-conversion mixer all in a 2mm2-size chip area. Time-domain transceiver operation is successfully measured with a 1-nS pulse width. This is the first demonstration of a fully-integrated, time-domain mm-wave EPR transceiver in silicon. Next, we present the design of a Wirelessly Synchronized Multi-chip Array (WSMA) in 65-nm CMOS. The proposed architecture makes use of a central wireless signal to synchronize a mm-wave array, eliminating the need for connecting wires between the array elements. Wireless injection locking of a single chip is successfully demonstrated and a 3-dB linewidth of 400 Hz at a carrier frequency of 50 GHz is achieved (stability ratio of 8 ppb). In addition, a 2-element WSMA with an array aperture greater than 20 wavelengths is demonstrated using the proposed transceiver architecture. The reported transceiver includes a receiving on-chip antenna, a low-noise amplifier, an injection-locked voltage-controlled oscillator, a buffer amplifier, an in-phase/quadrature generator, a phase shifter, a power amplifier, and a transmitting on-chip antenna. The chip is fabricated in a 65-nm CMOS process and occupies an area of 1.7 mm x 3.8 mm. This work sets the foundation for increasing the array aperture through wireless injection locking, extending traditional array systems into the high-resolution, narrow-beamwidth regime. Finally, a 500GHz 2×1 transmitter array based on the WSMA architecture is designed and implemented in 90nm SiGe BiCMOS technology. Wireless synchronization allows for coherent operation of the THz array and enables rapid scaling of the radiated power and narrowing of the array beamwidth. The RX consists of an on-chip dipole antenna, a phase shifter, buffers, and a frequency doubler. The TX consists of an injection-locked oscillator, buffers, power amplifiers, ×5 frequency multipliers and on-chip dipole antennas. Substrate cancellation enhances the array radiation efficiency. The multiplier-last architecture enables systematic and optimal design of the oscillator and the antenna. An output power of −10.3dBm at 500GHz is demonstrated in this design. The chip size is 2.2mm × 2.4mm.Item Wireless synchronization of mm-wave arrays(2018-10-23) Chen, Charles; Babakhani, Aydin; Rice University; United States Patent and Trademark OfficeSystems and methods providing wireless synchronization of wave arrays may include an antenna that receives a wireless injection signal and another antenna that radiates a locked wave signal corresponding to the injection signal. In some embodiments, these systems may also provide a low noise amplifier, voltage controlled oscillator (VCO), buffer amplifier(s), phase shifter, and/or multi-stage amplifier. In some embodiments, the injection signal may be provided on an even harmonic, and the intended transmission frequency signal is on an odd harmonic of the locked signal. The substrate thickness may be designed to radiate electromagnetic waves in odd harmonics of the locked signal. In yet another embodiment, polarization of a receiving antenna may be orthogonal to a transmitter antenna.