R-3 Repository :: Browsing by Author "Babakhani, Aydin"

Browsing by Author "Babakhani, Aydin"

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A Wirelessly Powered Injection-Locked Oscillator with On-Chip Antennas in CMOS for IOT Sensor Node
(2016-04-22) Sun, Yuxiang; Babakhani, Aydin
In recent years, the Internet of Things (IoT) has emerged as the main technology trend. By connecting every physical object embedded with sensors and actuators, the IoT merges with the real physical world to the virtual Internet world. This new network opens up tremendous opportunities in all kinds of applications, ranging from health care to autonomous car design to the oil and gas industry. However, the IoT network also presents many challenges. One important challenge is power source. Regularly changing the batteries of billions of IoT devices seems impossible. Nor can we run with billions of cables to connect these devices. One promising solution is using wireless power. In the past few decades, we have benefited from progessive CMOS technology to shrink the size of the silicon chip. However, as for antenna, there is a fundamental trade off between size, efficiency, and frequency. For IoT systems, a lot of optimization should be done to aggressively shrink the wireless powered chips with on-chip antennas to millimeter size. To address these issues, this thesis presents the first batteryless mm-sized wirelessly powered injection-locked oscillator with on-chip antennas in 180nm SOI CMOS. The chip harvests electromagnetic radiation from a continuous-wave source in the X-band using the on-chip antenna. In addition, the chip is equipped with a broadband injection-locking oscillator that locks to the frequency of the input and produces a synchronized signal at the half frequency of the input. The locked signal is then radiated back by the on-chip dipole antenna. This architecture resolves the conventional self-interference issues in RFID sensors by separating the received and transmitted frequencies. In addition, the locking mechanism improves the phase-noise of the on-chip oscillator to -93dBc/Hz at 100Hz offset.
An Integrated Germanium-Based THz Impulse Radiator with an Optical Waveguide Coupled Photoconductive Switch in Silicon
(MDPI, 2019) Chen, Peiyu; Hosseini, Mostafa; Babakhani, Aydin
This paper presents an integrated germanium (Ge)-based THz impulse radiator with an optical waveguide coupled photoconductive switch in a low-cost silicon-on-insulator (SOI) process. This process provides a Ge thin film, which is used as photoconductive material. To generate short THz impulses, N++ implant is added to the Ge thin film to reduce its photo-carrier lifetime to sub-picosecond for faster transient response. A bow-tie antenna is designed and connected to the photoconductive switch for radiation. To improve radiation efficiency, a silicon lens is attached to the substrate-side of the chip. This design features an optical-waveguide-enabled “horizontal” coupling mechanism between the optical excitation signal and the photoconductive switch. The THz emitter prototype works with 1550 nm femtosecond lasers. The radiated THz impulses achieve a full-width at half maximum (FWHM) of 1.14 ps and a bandwidth of 1.5 THz. The average radiated power is 0.337 μ W. Compared with conventional THz photoconductive antennas (PCAs), this design exhibits several advantages: First, it uses silicon-based technology, which reduces the fabrication cost; second, the excitation wavelength is 1550 nm, at which various low-cost laser sources operate; and third, in this design, the monolithic excitation mechanism between the excitation laser and the photoconductive switch enables on-chip programmable control of excitation signals for THz beam-steering.
Battery-less Transmitter and Frequency-Agile Receiver for IoT Applications
(2018-04-19) Li, Dai; Babakhani, Aydin
Recent increasing demands for IoT device, wearable device and biomedical implants have been calling for more low power, energy efficient and highly integrated devices from electronic industry. Implementing transmitter and energy-harvesting circuits on a same chip is a good way to provide battery-less systems for data transmission in wireless sensor networks. Prior wireless powered devices work used sub-gigahertz microwaves and require very large antenna for energy harvesting, which prevents their application in biomedical implants and single-chip integration. Our work on battery-less transmitter integrated on-chip antenna for 8 to 10 GHz wireless energy harvesting. This approach reduced antenna size and provided stable 10uW energy source for duty-cycled operating transmitter. The transmitter used On-Off Key (OOK) modulation. Oscillator, a class-E power amplifier and a dipole on-chip antenna are the main components of the transmitter. The transmitter operates at 1.46GHz and consumes 25mW power. The on-chip antenna is matched to the transmitter at 1.46GHz and could radiate up to -20dBm power into the air. By modulating from an external signal source, the data rate can be as high as 50M Bit/sec. The transmitter is able to harvest power from a radiating antenna 30cm away from the chip with a size of 7.4mm2 and transmit data back. Thus it is suitable for biomedical implant and wearable devices. On the other hand, our work introduced a frequency-agile receiver that detect and switch to the most power efficient channel quickly. The receiver consists of a band-switching low noise amplifier (LNA), an all-digital-phase-locked-loop (ADPLL), a power detector and a successive approximation analog to digital converter. The receiver worked at 4.3 to 5.7GHz and provide quick band-switching on the LNA and ADPLL. It provides quick and accurate channel selection in quickly changing environments.
Broadband Terahertz Signal Generation and Radiation Based on Direct Digital-to-Impulse Radiating Arrays in Silicon
(2018-04-16) Assefzadeh, Mahdi; Babakhani, Aydin; Knightly, Edward
Broadband terahertz (THz) signal generation and radiation has unique applications in 3-D hyper-spectral imaging, molecular sensing, and high-speed wireless communication. THz waves interact with the rotational and vibrational transitions of molecules with applications in material detection and biomedical sensing. They also penetrate through non-metallic and non-polar mediums that can be used to image concealed objects for security purposes. Conventional terahertz pulse generation techniques are based on the optical excitation of a III-V photoconductive antenna with a femtosecond optical laser pulse. This method of THz pulse generation and detection is widely used in THz time-domain spectroscopy systems. Although THz-TDS is a powerful technique, its dependence on bulky, expensive and power-hungry femtosecond lasers, optomechanical components, and costly photoconductive antennas compromises its speed, accessibility and scalability. In this dissertation, an on-chip laser-free direct digital-to-impulse (D2I) architecture is introduced that is capable of radiating a THz pulse by creating and exciting a broadband radiating resonator consisting of an on-chip antenna and a broadband matching network. This novel method converts a digital trigger edge to a radiated THz pulse with a high timing accuracy. A broadband matching network and an ON/OFF impulse-shaping technique are designed to maximize the amplitude of the pulse and minimize ringing. This method achieves a high DC-to-radiated efficiency by turning off the current switch shortly after turning it on. The deep nonlinear switching mechanism results in numerous harmonics from GHz to THz. Based on the high timing accuracy of the radiated THz pulses in D2I, a novel trigger-based beamforming architecture is introduced that enables broadband pulse beamforming in which all frequency content is steered simultaneously. This is in contrast with conventional phased-array architectures that have a limited bandwidth, where an RF signal is time-delayed. One of the main challenges of sampling a picosecond pulse in the time domain is ensuring that both the receiver and its antenna are broadband and have a linear phase response. Pyramidal horn antennas cannot be used to receive picosecond pulses, due to their limited bandwidth and nonlinear phase response. In addition, commercially available sampling oscilloscopes have a 3-dB bandwidth of less than 70 GHz, therefore cannot be used to sample a pulse with a FWHM of \textasciitilde 2 ps. To address this problem, we propose a direct time-domain measurement scheme based on femtosecond-laser-based THz sampling systems. Having a high-power, broadband frequency-comb source is critical in imaging and spectroscopy applications. By applying a periodic trigger signal, the D2I architecture radiates an impulse train in the time domain, which has a frequency-comb spectrum with a spacing of $1/T$. To perform spectroscopy, T can be controlled to sweep the whole spectrum. Further in this thesis, we will present our THz pulse radiating chips applied in imaging and spectroscopy experiments. This is the first time that a fully electronic chip is capable of generating and radiating harmonic tones at frequencies higher than 1 THz. Owing to the high scalability of the D2I architecture, combined with the broadband pulse beam-forming method, large arrays of D2I radiators can be built to radiate high-power, steerable narrow beams. In this thesis, ultra-short pulse radiating sources will be presented that were used to demonstrate laser-free broadband gas spectroscopy and THz imaging.
Design & Applications of Silicon-Based Picosecond Pulse Systems
(2018-04-19) Aggrawal, Himanshu; Babakhani, Aydin
Terahertz waves, which occupy the band from 0.1 mm to 1 mm, are unique in the spectrum because of their potential applications in secure communications, automotive radar, spectroscopy and medical imaging. Despite the interest in using terahertz waves, we currently lack the underlying hardware platform to build upon. Currently, the only way to sample a picosecond signal is via photoconductive detection with a femtosecond laser and a PCA (photo-conductive antenna). Such systems require an expensive laser, sensitive optical alignment, and a mechanical delay line to scan the sampling time, thus limiting the beneficiaries to a limited number of research laboratories and universities. My research investigates and builds next generation of THz receivers and samplers with few picosecond sampling window based on the integrated circuit technology. The goal is to implement laser-free, fully electronic samplers to sub-sample Terahertz signal.
Design of CMOS based High Temperature sensor with integrated memory
(2018-05-25) Cherivirala, Yaswanth Kumar; Babakhani, Aydin
Recent advances in various fields like high speed wireless communication links, big data processing etc., has enabled the implementation of large distributed sensor systems. And with the onset of the era of Internet of Things (IoT), demand for self-sustaining and efficient sensors is ever growing. Consequently, due to their economical and complex integration benefits, CMOS based sensors have gained a lot of attention in implementations of distributed sensor systems for vast number of applications. Applications of wireless distributed temperature sensor systems (WDTS) are often limited by the power consumed and area occupied by each sensor node. Recent works in building ultra-low power high temperature sensors has enabled the sensor core to operate on powers of the order of tens of µW to few hundred nW and occupy an area on the order of mm2. In this work, we propose a new ring oscillator based temperature sensor in 0.18µm CMOS SOI process is developed. A high resistive NOT gate is used as a single stage of the proposed ring oscillator to minimize the power consumed by the oscillator. The proposed oscillator generates oscillations of frequencies from 0.222 KHz to 13.089 KHz over a temperature range of 130°C to 260°C and consumes a maximum power of 2.052nW of power at 260°C. Also a low power custom SRAM with control digital circuitry is designed to be integrated with the sensor and energy harvesting blocks to develop a complete wireless temperature sensor node for geothermal reservoirs.
Design Techniques and Measurement Methods for Broadband Millimeter-Wave and THz Systems in Silicon
(2018-03-30) Chen, Peiyu; Babakhani, Aydin
Short impulses in millimeter-wave (mm-wave) and THz regimes (30 GHz - 30 THz) have a potentially large bandwidth that can be exploited for various applications, for example, high-resolution 3D imaging, high-speed wireless communication, broadband spectroscopy, etc. Existing methods for impulse generation have the following drawbacks: First, photonics solutions are usually not compatible with silicon technologies, i.e. CMOS and BiCMOS, impeding higher level SOC designs; Second, electronic oscillator-based solutions usually require phase-locked loop (PLL) and delay-locked loop (DLL) to ensure coherency of generated impulses, which increases system complexity, power consumption, and die area; Third, electronics digital-to-impulse solutions can be further improved by generating shorter impulses, reducing late-time ringing, and achieving amplitude modulation. In addition, high demands on using silicon technology to generate picosecond or sub-picosecond impulses impose challenges on standard chip characterization methods in both time domain and frequency domain. This dissertation demonstrates three chip designs and one chip characterization method to resolve the aforementioned drawbacks and challenges. The first chip design is to use a CMOS-compatible silicon photonics process technology to design a THz PCA chip, which can radiate 1.14 ps impulses. The prototype silicon photonics chip enables easier integrations with other photonics and electronics devices on a single chip. The second chip design is to implement an asymmetric-VCO-based impulse radiator without requiring any PLL or DLL in a 130 nm SiGe BiCMOS. With on-chip antennas, it radiates 60 ps impulses with less power consumption, system complexity, and die area than conventional oscillator-based solutions. The designed impulse radiator has also been applied for 3D imaging. The last chip design is to apply a new circuit technique, nonlinear Q-switching impedance, to implement a 4 ps impulse radiator with pulse amplitude modulation in a 130 nm SiGe BiCMOS. An optoelectronics-based time-domain characterization method was invented to test the 4 ps impulse radiator, and this new measurement technique shows a significant accuracy improvement compared with standard time-domain methods. The demonstrated techniques in this dissertation show that silicon technology is a promising solution to generating picosecond and even sub-picosecond impulses and it is approaching to the performance of photonics devices. Ultra-broadband silicon-based impulse radiators can be characterized using optoelectronics technology to achieve better measurement accuracy.
Electron paramagnetic resonance (EPR) systems and methods for flow assurance and logging
(2021-12-14) Babakhani, Aydin; Yang, Xuebei; Rice University; United States Patent and Trademark Office
An Electron Paramagnetic resonance (EPR) system and method allows the measurement paramagnetic characteristics of materials in real-time, such as heavy oil, hydrocarbons, asphaltenes, heptane, vanadium, resins, drilling fluid, mud, wax deposits or the like. The EPR systems and methods discussed herein are low cost, small and light weight, making them usable in flow-assurance or logging applications. The EPR sensor is capable of measuring paramagnetic properties of materials from a distance of several inches. In some embodiments, a window will be used to separate the EPR sensor from the materials in a pipeline or wellbore. Since the sensor does need to be in direct contact with the materials, it can operate at a lower temperature or pressure. In other embodiments, the EPR sensor may be placed in the materials.
Electron paramagnetic resonance (EPR) systems with active cancellation
(2020-05-26) Babakhani, Aydin; Yang, Xuebei; Rice University; United States Patent and Trademark Office
An active cancellation system may be utilized to cancel interference, such as from transmitter leakage or self-interference in a transceiver of an electron paramagnetic resonance (EPR) spectrometer. The active cancellation system may be inserted between the transmitter and receiver. The active cancellation system may receive the output of the transmitter, and generate a cancellation signal with the same amplitude, but phase shifted relative to the self-interference signal. The cancellation system may include an attenuator/amplitude tuner, buffer, VQ generator, and phase shifter.
Electron spin resonance for medical imaging
(2018-01-02) Yang, Xuebei; Chen, Charles; Seifi, Payam; Babakhani, Aydin; Rice University; United States Patent and Trademark Office
A 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.
EPR systems for flow assurance and logging
(2019-09-10) Babakhani, Aydin; Yang, Xuebei; Rice University; United States Patent and Trademark Office
An Electron Paramagnetic resonance (EPR) system and method allows the measurement paramagnetic characteristics of materials in real-time, such as heavy oil, hydrocarbons, asphaltenes, heptane, vanadium, resins, drilling fluid, mud, wax deposits or the like. The EPR systems and methods discussed herein are low cost, small and light weight, making them usable in flow-assurance or logging applications. The EPR sensor is capable of measuring paramagnetic properties of materials from a distance of several inches. In some embodiments, a window will be used to separate the EPR sensor from the materials in a pipeline or wellbore. Since the sensor does need to be in direct contact with the materials, it can operate at a lower temperature or pressure. In other embodiments, the EPR sensor may be placed in the materials.
Fully programmable digital-to-impulse radiating array
(2019-02-19) Assefzadeh, Mohammad Mahdi; Babakhani, Aydin; Rice University; United States Patent and Trademark Office
A fully-programmable digital-to-impulse radiator with a programmable delay is discussed herein. The impulse radiator may be part of an array of impulse radiators. Each individual element of the array may be equipped with an integrated programmable delay that can shift the timing of a digital trigger. The digital trigger may be fed to an amplifier, switch, and impulse matching circuitry, whereas the data signal path may be provided from a separate path. An antenna coupled to the impulse matching circuitry may then radiate ultra-short impulses. The radiating array may provide the ability to control delay at each individual element, perform near-ideal spatial combing, and/or beam steering.
High efficiency carbon nanotube thread antennas
(AIP Publishing, 2017) Bengio, E. Amram; Senic, Damir; Taylor, Lauren W.; Tsentalovich, Dmitri E.; Chen, Peiyu; Holloway, Christopher L.; Babakhani, Aydin; Long, Christian J.; Novotny, David R.; Booth, James C.; Orloff, Nathan D.; Pasquali, Matteo
Although previous research has explored the underlying theory of high-frequency behavior of carbon nanotubes (CNTs) and CNT bundles for antennas, there is a gap in the literature for direct experimental measurements of radiation efficiency. These measurements are crucial for any practical application of CNT materials in wireless communication. In this letter, we report a measurement technique to accurately characterize the radiation efficiency of λ/4 monopole antennas made from the CNT thread. We measure the highest absolute values of radiation efficiency for CNT antennas of any type, matching that of copper wire. To capture the weight savings, we propose a specific radiation efficiency metric and show that these CNT antennas exceed copper's performance by over an order of magnitude at 1 GHz and 2.4 GHz. We also report direct experimental observation that, contrary to metals, the radiation efficiency of the CNT thread improves significantly at higher frequencies. These results pave the way for practical applications of CNT thread antennas, particularly in the aerospace and wearable electronics industries where weight saving is a priority.
High-resolution Millimeter-wave Impulse-based MIMO 3D Imaging Radar in Silicon
(2015-04-22) Chen, Peiyu; Babakhani, Aydin; Aazhang, Behnaam; Knightly, Edward W; Kono, Junichiro
The research on millimeter-wave (mm-wave) silicon-based integrated 3D imaging radar has gained tremendous attention in academia over the past decade. Compared with conventional 2D imaging, 3D imaging captures both 1D depth information and 2D intensity maps. Impulse-based 3D imaging radar can also obtains more constitutional information of objects, like spectroscopy, so as to potentially have material identification functionality with 3D imaging simultaneously. The main objectives in the roadmapping of silicon integrated 3D imaging radar are higher image resolution, a larger image range and shorter acquisition time. With the dramatically improved performance of silicon transistors, mm-wave circuits using CMOS and BiCMOS technologies can generate picosecond-level impulses but with small RF power. Shorter impulses provide higher image resolution, but small RF power limits image range. Spatially coherent impulse combining from multiple silicon circuits is the solution to this problem. Compared with narrow-band phased-arrays that perform only 2D spatial filtering and have range-ambiguity problems, impulse-radiating arrays are capable of performing 3D spatial filtering that enhances the imaging sensitivity of a certain point in 3D space without sacrificing image resolution. Therefore, impulse-based MIMO imaging radar can achieve both high resolution and a large image range simultaneously. In this present work, a 60ps impulse radiator with an on-chip antenna is implemented in the IBM 130nm SiGe BiCMOS process technology. The impulse radiator is the core element of the synthetic arrays that are used to perform 3D imaging in this thesis. A pulsed-VCO-based architecture is designed based on an asymmetric cross-coupled pulsed VCO to convert a digital input signal to radiated impulses. The deliberate asymmetry in the pulsed VCO is introduced to minimize the timing jitter of the radiated impulses in order to achieve spatially coherent impulse combining with high efficiency. The radiated impulses have a record RMS jitter of 178fs with 64 averaging when the input trigger signal has a RMS jitter of 150fs. Two widely spaced impulse radiators are used to perform spatially coherent impulse combining with an efficiency of 98.7%. As the first step in demonstrating impulse-based MIMO 3D imaging radar, in this work, custom synthetic array imaging systems were built based on the proposed silicon-based integrated impulse radiator. 3D imaging of metallic and dielectric objects (rocks immersed in oil) have been performed successfully. A depth accuracy of 27um, a depth resolution of 9mm and a lateral resolution of 8mm at 10cm distance in the air have been achieved. To the author’s knowledge, this work demonstrates the first high-resolution 3D images that are generated by using synthetic array imaging systems based on a fully-integrated impulse radiator in silicon. Future work includes implementing fully integrated impulse transceivers and fully integrated impulse-based MIMO 3D imaging radar with independent time-delay controls.
High-speed Track and Hold Amplifiers in CMOS for Enabling Pulse-based Direct Modulation, Secure Communication and Precision Localization
(2015-08-06) Aggrawal, Himanshu; Babakhani, Aydin; Cavallaro, Joseph; Mittleman, Daniel
Last few decades have seen a puissant desire for fast communication links that has shaped the evolution of high-speed circuits and silicon- based technology. This desire accompanied with a large consumer market has fueled the development of ever-shrinking, faster technology nodes. These advanced nodes open doors for designers to develop new ways of transferring data with unprecedented speed and accuracy. There are a number of challenges in building high-speed, secure communication links, one being the lack of availability of fast Analog to Digital Converters (ADCs), which form the front end of a receiver. Even in advanced technology nodes, the leakage in the transmission gate due to parasitic source-drain capacitance provides an alternate path for signals to pass, thus lowering the performance of the ADCs at high frequencies. Second, the current communication schemes use beam-forming or Direct Antenna Modulation (DAM) to narrow the information beam and point it in the direction of communication. Such techniques still have a wide information beam compared pulse-based directional modulation, as discussed in this thesis. In this dissertation, we address the issue of parasitic leakages in the transmission gate of a fast sampler by introducing active cancellation. A track-and-hold amplifier with active cancellation is designed and fabricated in 45nm CMOS SOI technology, which can operate at 40GSample/second real-time. In addition to this, we also study a pulse-based directional modulation scheme which can be used for secure communication, imaging and localization. Two coherent pulse generators with pulse width less than 200ps were used to attain an information beamwidth of less than 1 degree and localize objects with millimeter accuracy.
Impulse sampler architecture and active clock cancellation architecture
(2019-02-12) Aggrawal, Himanshu; Babakhani, Aydin; Rice University; United States Patent and Trademark Office
A novel nonlinear impulse sampler is presented that provides a clock sharpening circuit, sampling stage, and post-sampling block. The clock sharpening circuit sharpens the incoming clock while acting as a buffer, and the sharpened clock is fed to the input of the sampling stage. The impulse sampling stage has two main transistors, where one transistor generates the impulse and the other transistor samples the input signal. Post-sampling block processes the sampled signal and acts as a sample and hold circuit. The architecture uses an ultrafast transmission-line based inductive peaking technique to turn on a high-speed sampling bipolar transistor for a few picoseconds. It is shown that the sampler can detect impulses as short as 100 psec or less.
Integrated Electromagnetic Wireless Power Harvesting System for mm-size Biomedical Implants
(2017-04-18) Rahmani, Hamed; Babakhani, Aydin
Rising demand for continuous monitoring of human body and health care devices in recent years has resulted in the development of implantable biopotential sensors. Infection risks and mobility concerns constrain the implanted sensors to operate without any transcutaneous wire connection which raises serious challenges for powering and data telemetry. Lack of enough information on many physiological processes such as human speech production dynamics has hindered research on bases of the processes and it mainly stems from available measurement systems limitations. In this work, we use electromagnetic waves in GHz frequency range to transfer the required power to the implanted system. The optimum frequency for wireless power transfer is studied as a function of transmitting and receiving antennas as well as the dispersive characteristics of the biological tissues. We present two types of power harvesting platform with on-chip antennas that can be integrated on a silicon chip. The second power harvesting system is designed to have a long-range operating range and harvests electrical energy from a far-field electromagnetic source and can be exploited to power up ultra-low power biomedical implants. The second system is designed to increase the functionality of a complex implant such as a neural recording system. While maintaining the losses in biological tissues below Specific Absorption Rate (SAR) limit, the harvesting system can provide milliwatts of power the operation of a high performance fully integrated biomedical implant.
Integrated Millimeter-Wave and Sub-Terahertz Pulse Receivers for Wireless Time Transfer and Broadband Sensing
(2019-12-03) Jamali, Babak; Babakhani, Aydin; Knightly, Edward W.
Broadband sensing and spectroscopy in millimeter-wave and sub-THz frequencies can be facilitated with CMOS integrated circuits as low-cost, compact solutions. Wireless integrated systems in the mm-wave/THz regime pave the path for various novel applications, such as high-resolution imaging, broadband spectroscopy, and high-speed communication. Particularly, generation and detection of ultra-short picosecond pulses on silicon platforms have been of interest to researchers due to enhanced tunability and bandwidth of such signals. In this dissertation, silicon-based ultra-short pulse detectors are studied with special focus on two primary applications: wireless time transfer with sub-picosecond accuracy and broadband spectroscopy and sensing. First, a self-mixing mm-wave impulse detector is introduced for high-accuracy wireless clock synchronization. Measurement results of the fabricated silicon chip demonstrate that a low-jitter sub-10GHz clock signal can be distributed among widely spaced nodes in a large-aperture array. Such a synchronized large-aperture array can enhance the angular resolution in imaging radars. Secondly, a CMOS impulse detector with center frequency of 77 GHz is presented to achieve low-jitter inter-chip wireless time transfer. This impulse detector, which includes an on-chip slot planar inverted cone antenna, is based on a three-stage divide-by-8 injection-locked frequency divider. It is shown that a three-stage divider has better input sensitivity than a single-stage divide-by-8 divider. The output of the receiver is locked to the input repetition rate with an rms jitter of 0.29 ps. A wireless time transfer test with two impulse detector chips demonstrates that a low-jitter 9.5-GHz clock is distributed among widely spaced nodes in a large-aperture array. Finally, a fully integrated coherent detector is introduced which uses a broadband frequency comb as a reference to detect mm-wave and sub-THz signals. The tunable frequency comb, which is generated by high-speed current switches, drives a passive field-effect transistor mixer to down-convert signals captured by an on-chip antenna. This system is capable of detecting any arbitrary spectrum from 50 to 280 GHz with a minimum resolution of 2 Hz. The detector circuit consumes a dc power of 34 mW, which makes it a low-power solution in comparison with conventional mm-wave/THz systems. This detector is utilized as a spectroscopic sensor to characterize different materials based on their responses to mm-wave signals.
Intergrated electron spin resonance spectrometer
(2017-06-27) Yang, Xuebei; Chen, Charles; Seifi, Payam; Babakhani, Aydin; Rice University; United States Patent and Trademark Office
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. 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.
Methods and related systems of ultra-short pulse detection
(2019-01-29) Babakhani, Aydin; Jamali, Babak; Rice University; United States Patent and Trademark Office
Ultra-short pulse detection. At least some example embodiments are methods including: receiving by an antenna a series of ultra-short pulses of electromagnetic energy at a repetition frequency, the receiving creates a pulse signal; self-mixing or intermodulating the pulse signal by applying the pulse signal to a non-linear electrical device, thereby creating a modulated signal; and filtering the modulated signal to recover a filtered signal having an intermodulated frequency being the repetition frequency.

Browsing by Author "Babakhani, Aydin"

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