MA
M. Alonso Del Pino
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This thesis presents the integration and evaluation of a 24-pixel silicon-germanium bipolar complementary metal-oxide-semiconductor terahertz camera in an active illumination transmission imaging setup. The camera had previously been characterized at detector level, but its performance as part of a complete imaging system still had to be evaluated. The main objective was therefore to determine whether the camera could produce repeatable and interpretable images when combined with the available quasi-optical measurement system. Two MATLAB-based graphical user interfaces were developed. The first interface predicts the expected image resolution for a selected camera configuration, frequency, and sample image. This allows for the expected visibility of object features to be estimated before measurement. The second interface controls the measurement workflow by configuring the source, detector bias supply, readout electronics, data-acquisition hardware, and mechanical positioning system. It provides hardware selection, connection testing, scan definition, live image preview, metadata storage, and image reconstruction from the measured pixel responses. Active imaging measurements were performed on an ivy leaf sample. The measured detector responses were mapped to spatial scan positions, converted to decibels, normalized, and then reconstructed into terahertz transmission images. The main result was obtained around 400 gigahertz, where the leaf outline and central vein were visible in the reconstructed image. Frequency averaging over five neighboring frequency points reduced background variations such as standing waves, while preserving the main leaf structure. The results show that the integrated system can produce interpretable active terahertz images and that the developed workflow supports controlled and reproducible measurements. However, the demonstrated performance is still limited by mechanical scanning time, optical alignment uncertainty, standing-wave artifacts, and pixel-dependent response differences.
...
This thesis presents the integration and evaluation of a 24-pixel silicon-germanium bipolar complementary metal-oxide-semiconductor terahertz camera in an active illumination transmission imaging setup. The camera had previously been characterized at detector level, but its performance as part of a complete imaging system still had to be evaluated. The main objective was therefore to determine whether the camera could produce repeatable and interpretable images when combined with the available quasi-optical measurement system. Two MATLAB-based graphical user interfaces were developed. The first interface predicts the expected image resolution for a selected camera configuration, frequency, and sample image. This allows for the expected visibility of object features to be estimated before measurement. The second interface controls the measurement workflow by configuring the source, detector bias supply, readout electronics, data-acquisition hardware, and mechanical positioning system. It provides hardware selection, connection testing, scan definition, live image preview, metadata storage, and image reconstruction from the measured pixel responses. Active imaging measurements were performed on an ivy leaf sample. The measured detector responses were mapped to spatial scan positions, converted to decibels, normalized, and then reconstructed into terahertz transmission images. The main result was obtained around 400 gigahertz, where the leaf outline and central vein were visible in the reconstructed image. Frequency averaging over five neighboring frequency points reduced background variations such as standing waves, while preserving the main leaf structure. The results show that the integrated system can produce interpretable active terahertz images and that the developed workflow supports controlled and reproducible measurements. However, the demonstrated performance is still limited by mechanical scanning time, optical alignment uncertainty, standing-wave artifacts, and pixel-dependent response differences.
Silicon-Integrated Arrays for Passive Terahertz Cameras
Towards Compact and High-Resolution Imaging using Direct Detectors
The short wavelengths and wide available bandwidth in the terahertz (THz) regime make it an attractive frequency range for commercial, passive imaging applications. Fully exploiting these benefits requires low-cost THz imaging solutions with a high density of beams and excellent temperature sensitivity. Thanks to advancements in the temperature sensitivity of direct detectors integrated in processes such as CMOS and SiGe, commercially available silicon platforms have become the most promising candidates for a low-cost THz camera. Integrating these detectors in dense, large focal plane arrays (FPAs) operating over ultra-wide bandwidths would yield a camera capable of passive imaging with a diffraction-limited resolution. This thesis describes the design and characterization of arrays integrated in both CMOS and SiGe BiCMOS towards realizing such a passive THz camera.
To explore the realization of such a camera, we first extensively characterized a previously proposed chessboard FPA that was designed to achieve a near diffractionlimited resolution. This chessboard FPA was integrated with direct detectors based on Schottky diodes in 22-nm CMOS, and operates from 200 GHz to 600 GHz. Characterization was performed using an over-the-air measurement setup, enabling 2-D, multi-beam pattern characterization with a high dynamic range. Measurements of both the aperture efficiency and beam overlap between adjacent pixels demonstrated that the fabricated chessboard FPA improves gain at the edge-of-coverage by 1.2dB compared to an ideal hexagonal FPA of uniform feeds. The chessboard configuration therefore combines state-of-the-art focal plane sampling with minimal penalty in antenna efficiency.
Building on these results, we designed a quasi-optical system to validate the imaging performance of the CMOS-integrated FPA in a practical scenario. Since the Schottky diodes in the FPA did not enable passive imaging, active illumination of the sample was required to achieve sufficient imaging dynamic range. The quasi-optical system was optimized to ensure that the imaging resolution was dictated solely by the focal plane sampling in the chessboard FPA, while maintaining sufficient coupling between all pixels and the active source. Using this system, we performed an imaging demonstration of an ivy leaf hidden in an envelope, further emphasizing the state-of-the-art spatial resolution of the chessboard FPA.
While the CMOS-integrated chessboard FPA demonstrated excellent spatial resolution, its temperature sensitivity was insufficient for passive imaging. To overcome this limitation, we designed the chessboard FPA in a 130-nm SiGe BiCMOS process, utilizing heterojunction bipolar transistors (HBTs) to implement the direct detectors. The implemented chessboard FPA operates between 250 GHz – 600 GHz, and features detectors employing deeply saturated HBTs in a common-base configuration. The prototype was characterized using the quasi-optical system designed for the imaging demonstration. Measurements of the radiation patterns and responsivity showed good agreement with simulations, although the noise-equivalent power was higher than expected. Nevertheless, it is still competitive with the state-of-the-art and should enable passive THz imaging. The noise-equivalent temperature difference was estimated to be 1.6K for a 1 s integration time.
A critical challenge for passive THz cameras is low-frequency noise injected by the direct detectors. To address this, we proposed a solid-state chopper based on a reconfigurable periodic surface. The chopping operation is realized by electronically controlling the transmission through this surface, which is both more compact and faster than a mechanical chopping wheel, while preserving the spatial sampling of the chessboard FPA. The chopper was implemented in 130-nm SiGe BiCMOS and consists of sub-wavelength metal patches in a chessboard geometry loaded with varactor-connected MOSFETs. For characterization, a quasi-optical system was developed, consisting of two elliptical silicon lenses with the chopper located at the shared focus. Measurements showed that the chopper transmission was significantly lower than simulated. When using impedance measurements of a single MOSFET device to re-simulate the chopper, a considerably better match with simulations was obtained. To achieve the desired chopper performance, an alternative implementation was designed based on the measured impedance of an HBT-based load. Although this design has not yet been fabricated, simulations indicate it should enable passive imaging performance when combined with a state-of-the-art antenna-coupled direct detector. Since this design is based on device measurements, there is a high confidence that this proposed chopper design contributes towards the realization of a compact, passive THz camera with near diffraction-limited resolution.
...
To explore the realization of such a camera, we first extensively characterized a previously proposed chessboard FPA that was designed to achieve a near diffractionlimited resolution. This chessboard FPA was integrated with direct detectors based on Schottky diodes in 22-nm CMOS, and operates from 200 GHz to 600 GHz. Characterization was performed using an over-the-air measurement setup, enabling 2-D, multi-beam pattern characterization with a high dynamic range. Measurements of both the aperture efficiency and beam overlap between adjacent pixels demonstrated that the fabricated chessboard FPA improves gain at the edge-of-coverage by 1.2dB compared to an ideal hexagonal FPA of uniform feeds. The chessboard configuration therefore combines state-of-the-art focal plane sampling with minimal penalty in antenna efficiency.
Building on these results, we designed a quasi-optical system to validate the imaging performance of the CMOS-integrated FPA in a practical scenario. Since the Schottky diodes in the FPA did not enable passive imaging, active illumination of the sample was required to achieve sufficient imaging dynamic range. The quasi-optical system was optimized to ensure that the imaging resolution was dictated solely by the focal plane sampling in the chessboard FPA, while maintaining sufficient coupling between all pixels and the active source. Using this system, we performed an imaging demonstration of an ivy leaf hidden in an envelope, further emphasizing the state-of-the-art spatial resolution of the chessboard FPA.
While the CMOS-integrated chessboard FPA demonstrated excellent spatial resolution, its temperature sensitivity was insufficient for passive imaging. To overcome this limitation, we designed the chessboard FPA in a 130-nm SiGe BiCMOS process, utilizing heterojunction bipolar transistors (HBTs) to implement the direct detectors. The implemented chessboard FPA operates between 250 GHz – 600 GHz, and features detectors employing deeply saturated HBTs in a common-base configuration. The prototype was characterized using the quasi-optical system designed for the imaging demonstration. Measurements of the radiation patterns and responsivity showed good agreement with simulations, although the noise-equivalent power was higher than expected. Nevertheless, it is still competitive with the state-of-the-art and should enable passive THz imaging. The noise-equivalent temperature difference was estimated to be 1.6K for a 1 s integration time.
A critical challenge for passive THz cameras is low-frequency noise injected by the direct detectors. To address this, we proposed a solid-state chopper based on a reconfigurable periodic surface. The chopping operation is realized by electronically controlling the transmission through this surface, which is both more compact and faster than a mechanical chopping wheel, while preserving the spatial sampling of the chessboard FPA. The chopper was implemented in 130-nm SiGe BiCMOS and consists of sub-wavelength metal patches in a chessboard geometry loaded with varactor-connected MOSFETs. For characterization, a quasi-optical system was developed, consisting of two elliptical silicon lenses with the chopper located at the shared focus. Measurements showed that the chopper transmission was significantly lower than simulated. When using impedance measurements of a single MOSFET device to re-simulate the chopper, a considerably better match with simulations was obtained. To achieve the desired chopper performance, an alternative implementation was designed based on the measured impedance of an HBT-based load. Although this design has not yet been fabricated, simulations indicate it should enable passive imaging performance when combined with a state-of-the-art antenna-coupled direct detector. Since this design is based on device measurements, there is a high confidence that this proposed chopper design contributes towards the realization of a compact, passive THz camera with near diffraction-limited resolution.
...
The short wavelengths and wide available bandwidth in the terahertz (THz) regime make it an attractive frequency range for commercial, passive imaging applications. Fully exploiting these benefits requires low-cost THz imaging solutions with a high density of beams and excellent temperature sensitivity. Thanks to advancements in the temperature sensitivity of direct detectors integrated in processes such as CMOS and SiGe, commercially available silicon platforms have become the most promising candidates for a low-cost THz camera. Integrating these detectors in dense, large focal plane arrays (FPAs) operating over ultra-wide bandwidths would yield a camera capable of passive imaging with a diffraction-limited resolution. This thesis describes the design and characterization of arrays integrated in both CMOS and SiGe BiCMOS towards realizing such a passive THz camera.
To explore the realization of such a camera, we first extensively characterized a previously proposed chessboard FPA that was designed to achieve a near diffractionlimited resolution. This chessboard FPA was integrated with direct detectors based on Schottky diodes in 22-nm CMOS, and operates from 200 GHz to 600 GHz. Characterization was performed using an over-the-air measurement setup, enabling 2-D, multi-beam pattern characterization with a high dynamic range. Measurements of both the aperture efficiency and beam overlap between adjacent pixels demonstrated that the fabricated chessboard FPA improves gain at the edge-of-coverage by 1.2dB compared to an ideal hexagonal FPA of uniform feeds. The chessboard configuration therefore combines state-of-the-art focal plane sampling with minimal penalty in antenna efficiency.
Building on these results, we designed a quasi-optical system to validate the imaging performance of the CMOS-integrated FPA in a practical scenario. Since the Schottky diodes in the FPA did not enable passive imaging, active illumination of the sample was required to achieve sufficient imaging dynamic range. The quasi-optical system was optimized to ensure that the imaging resolution was dictated solely by the focal plane sampling in the chessboard FPA, while maintaining sufficient coupling between all pixels and the active source. Using this system, we performed an imaging demonstration of an ivy leaf hidden in an envelope, further emphasizing the state-of-the-art spatial resolution of the chessboard FPA.
While the CMOS-integrated chessboard FPA demonstrated excellent spatial resolution, its temperature sensitivity was insufficient for passive imaging. To overcome this limitation, we designed the chessboard FPA in a 130-nm SiGe BiCMOS process, utilizing heterojunction bipolar transistors (HBTs) to implement the direct detectors. The implemented chessboard FPA operates between 250 GHz – 600 GHz, and features detectors employing deeply saturated HBTs in a common-base configuration. The prototype was characterized using the quasi-optical system designed for the imaging demonstration. Measurements of the radiation patterns and responsivity showed good agreement with simulations, although the noise-equivalent power was higher than expected. Nevertheless, it is still competitive with the state-of-the-art and should enable passive THz imaging. The noise-equivalent temperature difference was estimated to be 1.6K for a 1 s integration time.
A critical challenge for passive THz cameras is low-frequency noise injected by the direct detectors. To address this, we proposed a solid-state chopper based on a reconfigurable periodic surface. The chopping operation is realized by electronically controlling the transmission through this surface, which is both more compact and faster than a mechanical chopping wheel, while preserving the spatial sampling of the chessboard FPA. The chopper was implemented in 130-nm SiGe BiCMOS and consists of sub-wavelength metal patches in a chessboard geometry loaded with varactor-connected MOSFETs. For characterization, a quasi-optical system was developed, consisting of two elliptical silicon lenses with the chopper located at the shared focus. Measurements showed that the chopper transmission was significantly lower than simulated. When using impedance measurements of a single MOSFET device to re-simulate the chopper, a considerably better match with simulations was obtained. To achieve the desired chopper performance, an alternative implementation was designed based on the measured impedance of an HBT-based load. Although this design has not yet been fabricated, simulations indicate it should enable passive imaging performance when combined with a state-of-the-art antenna-coupled direct detector. Since this design is based on device measurements, there is a high confidence that this proposed chopper design contributes towards the realization of a compact, passive THz camera with near diffraction-limited resolution.
To explore the realization of such a camera, we first extensively characterized a previously proposed chessboard FPA that was designed to achieve a near diffractionlimited resolution. This chessboard FPA was integrated with direct detectors based on Schottky diodes in 22-nm CMOS, and operates from 200 GHz to 600 GHz. Characterization was performed using an over-the-air measurement setup, enabling 2-D, multi-beam pattern characterization with a high dynamic range. Measurements of both the aperture efficiency and beam overlap between adjacent pixels demonstrated that the fabricated chessboard FPA improves gain at the edge-of-coverage by 1.2dB compared to an ideal hexagonal FPA of uniform feeds. The chessboard configuration therefore combines state-of-the-art focal plane sampling with minimal penalty in antenna efficiency.
Building on these results, we designed a quasi-optical system to validate the imaging performance of the CMOS-integrated FPA in a practical scenario. Since the Schottky diodes in the FPA did not enable passive imaging, active illumination of the sample was required to achieve sufficient imaging dynamic range. The quasi-optical system was optimized to ensure that the imaging resolution was dictated solely by the focal plane sampling in the chessboard FPA, while maintaining sufficient coupling between all pixels and the active source. Using this system, we performed an imaging demonstration of an ivy leaf hidden in an envelope, further emphasizing the state-of-the-art spatial resolution of the chessboard FPA.
While the CMOS-integrated chessboard FPA demonstrated excellent spatial resolution, its temperature sensitivity was insufficient for passive imaging. To overcome this limitation, we designed the chessboard FPA in a 130-nm SiGe BiCMOS process, utilizing heterojunction bipolar transistors (HBTs) to implement the direct detectors. The implemented chessboard FPA operates between 250 GHz – 600 GHz, and features detectors employing deeply saturated HBTs in a common-base configuration. The prototype was characterized using the quasi-optical system designed for the imaging demonstration. Measurements of the radiation patterns and responsivity showed good agreement with simulations, although the noise-equivalent power was higher than expected. Nevertheless, it is still competitive with the state-of-the-art and should enable passive THz imaging. The noise-equivalent temperature difference was estimated to be 1.6K for a 1 s integration time.
A critical challenge for passive THz cameras is low-frequency noise injected by the direct detectors. To address this, we proposed a solid-state chopper based on a reconfigurable periodic surface. The chopping operation is realized by electronically controlling the transmission through this surface, which is both more compact and faster than a mechanical chopping wheel, while preserving the spatial sampling of the chessboard FPA. The chopper was implemented in 130-nm SiGe BiCMOS and consists of sub-wavelength metal patches in a chessboard geometry loaded with varactor-connected MOSFETs. For characterization, a quasi-optical system was developed, consisting of two elliptical silicon lenses with the chopper located at the shared focus. Measurements showed that the chopper transmission was significantly lower than simulated. When using impedance measurements of a single MOSFET device to re-simulate the chopper, a considerably better match with simulations was obtained. To achieve the desired chopper performance, an alternative implementation was designed based on the measured impedance of an HBT-based load. Although this design has not yet been fabricated, simulations indicate it should enable passive imaging performance when combined with a state-of-the-art antenna-coupled direct detector. Since this design is based on device measurements, there is a high confidence that this proposed chopper design contributes towards the realization of a compact, passive THz camera with near diffraction-limited resolution.
Wireless Radio Frequency (RF) systems have revolutionized the way we transmit and receive information from mobile platforms. In recent decades, the number of applications relying on wireless technologies, including telecommunications, radar, and sensing, have exploded. RF engineers have pushed the technological boundaries to feed our appetite for more information through the wireless networks. However, congestion in the low-frequency radio spectrum means that applications are in a continuous battle to be as spectrally efficient in the frequency bands allocated to them. This strategy has worked well for many wireless generations, but has added considerable challenges due to increased system complexity and decaying energy efficiency.....
...
Wireless Radio Frequency (RF) systems have revolutionized the way we transmit and receive information from mobile platforms. In recent decades, the number of applications relying on wireless technologies, including telecommunications, radar, and sensing, have exploded. RF engineers have pushed the technological boundaries to feed our appetite for more information through the wireless networks. However, congestion in the low-frequency radio spectrum means that applications are in a continuous battle to be as spectrally efficient in the frequency bands allocated to them. This strategy has worked well for many wireless generations, but has added considerable challenges due to increased system complexity and decaying energy efficiency.....
Master thesis
(2025)
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T.O. Geerling, M. Alonso Del Pino, M. Spirito, N. Llombart Juan, F. Sebastiano
Two devices, a SiGe BiCMOS MOSFET and a SiGe HBT, were characterized through on-wafer measurements in the 220–500 GHz range. The results showed that the PDK model of the MOSFET did not accurately represent the device. Conventional open–short de-embedding was found to lose accuracy at sub-THz frequencies due to its inherent lumped-element approximation. To address this limitation, an improved de-embedding method was developed by estimating a correction matrix A′ using transmission-line equivalent circuits, achieving up to 15.6 dB improvement in S11 and S22 for an HBT interconnect in simulation compared to the classical approach. The characterized MOSFET was used to simulate the integrated chopper transmissivity, which closely matched over-the-air measurements. The HBT characterization showed better agreement with the PDK, but the higher characterized capacitance resulted in reduced chopper performance.
...
Two devices, a SiGe BiCMOS MOSFET and a SiGe HBT, were characterized through on-wafer measurements in the 220–500 GHz range. The results showed that the PDK model of the MOSFET did not accurately represent the device. Conventional open–short de-embedding was found to lose accuracy at sub-THz frequencies due to its inherent lumped-element approximation. To address this limitation, an improved de-embedding method was developed by estimating a correction matrix A′ using transmission-line equivalent circuits, achieving up to 15.6 dB improvement in S11 and S22 for an HBT interconnect in simulation compared to the classical approach. The characterized MOSFET was used to simulate the integrated chopper transmissivity, which closely matched over-the-air measurements. The HBT characterization showed better agreement with the PDK, but the higher characterized capacitance resulted in reduced chopper performance.
This work aims to build a measurement test bench for wideband mixer EVM characterization at sub-terahertz frequencies. A VNA based setups with two frequency extenders are implemented. While one of the VNA sources can be used as the LO input, the other source will be swept over a frequency grid so that the RF output of the mixer under test will be down converted and read out tone by tone. Then the modulated signals are expected be reconstructed from the frequency domain measurement result, which will be demodulated for EVM characterization. A two-tier calibration method is used to extract the absolute power from the target RF channel. The key performance of the mixer under test, such as conversion loss, image rejection ratio and linearity are measured over an IF bandwidth up to 4GHz. Nevertheless, the major challenge for VNA based EVM measurements are the unhandled phase between the two sources of VNA, preventing the system to reconstruct a stable time domain signal. To solve this problem, an auxiliary phase channel setup is proposed, which can carry the unhandled phase information from one of the VNA source, thus providing a stable phase measurement for EVM measurements. To validate the proposed setups, the adjusted phase is derived from measurement results of the MUT channel and the results from the auxiliary channel. A phase stability of $\pm$5 degrees can be achieved with the proposed setups. Finally, EVM characterization is performed based on the proposed setup. A EVM floor of -30dB is achieved with a 300MHz QPSK signal, the error due to thermal noise is reduced due to the narrow band receiver of the VNA.
...
This work aims to build a measurement test bench for wideband mixer EVM characterization at sub-terahertz frequencies. A VNA based setups with two frequency extenders are implemented. While one of the VNA sources can be used as the LO input, the other source will be swept over a frequency grid so that the RF output of the mixer under test will be down converted and read out tone by tone. Then the modulated signals are expected be reconstructed from the frequency domain measurement result, which will be demodulated for EVM characterization. A two-tier calibration method is used to extract the absolute power from the target RF channel. The key performance of the mixer under test, such as conversion loss, image rejection ratio and linearity are measured over an IF bandwidth up to 4GHz. Nevertheless, the major challenge for VNA based EVM measurements are the unhandled phase between the two sources of VNA, preventing the system to reconstruct a stable time domain signal. To solve this problem, an auxiliary phase channel setup is proposed, which can carry the unhandled phase information from one of the VNA source, thus providing a stable phase measurement for EVM measurements. To validate the proposed setups, the adjusted phase is derived from measurement results of the MUT channel and the results from the auxiliary channel. A phase stability of $\pm$5 degrees can be achieved with the proposed setups. Finally, EVM characterization is performed based on the proposed setup. A EVM floor of -30dB is achieved with a 300MHz QPSK signal, the error due to thermal noise is reduced due to the narrow band receiver of the VNA.
This work demonstrates the imaging of (near) diffraction-limited images in the THz domain using a CMOS integrated camera. A Quasi Optical Setup is fabricated, aligned the radiation patterns and losses are characterized.
...
This work demonstrates the imaging of (near) diffraction-limited images in the THz domain using a CMOS integrated camera. A Quasi Optical Setup is fabricated, aligned the radiation patterns and losses are characterized.
Front-end Monolithic Microwave Integrated Circuits (MMICs) have recently become commercially available for frequencies above 100 GHz. However, achieving low-loss and broadband interconnections between the antenna and MMICs is challenging for integrated front ends at these frequencies. This thesis presents the characterization of a flip-chip interconnection used for an integrated front end at 150 GHz (G-band) with an on-package leaky-wave dual lens antenna. Two paths for the front-end integration have been proposed. The first path adopts CPW transmission lines on 500 μm-thick fused silica and provides easy assembly and seamless flip-chip capabilities. The second uses microstrip transmission lines on 50 μm-thick fused silica and provides lower transmission line loss but a challenging assembly and flip-chip interconnection. In this thesis, a path toward microstrip and CPW flip-chip interconnections has been outlined at the high millimeter-wave frequencies. Two-port test structures using CPW transmission lines were developed, adopting a double Thru-Reflect-Line calibration and allowing for accurate extracting of the interconnection response. The final interconnection to the MMICs has been realized using a via-less CPW to microstrip transition with high impedance transmission line S11 matching compensation. The simulated S11 and S22 are below -12 dB, Ohmic loss below 0.6 dB, radiation loss below 0.4 dB, and transmission line losses around 0.15 dB/mm.
...
Front-end Monolithic Microwave Integrated Circuits (MMICs) have recently become commercially available for frequencies above 100 GHz. However, achieving low-loss and broadband interconnections between the antenna and MMICs is challenging for integrated front ends at these frequencies. This thesis presents the characterization of a flip-chip interconnection used for an integrated front end at 150 GHz (G-band) with an on-package leaky-wave dual lens antenna. Two paths for the front-end integration have been proposed. The first path adopts CPW transmission lines on 500 μm-thick fused silica and provides easy assembly and seamless flip-chip capabilities. The second uses microstrip transmission lines on 50 μm-thick fused silica and provides lower transmission line loss but a challenging assembly and flip-chip interconnection. In this thesis, a path toward microstrip and CPW flip-chip interconnections has been outlined at the high millimeter-wave frequencies. Two-port test structures using CPW transmission lines were developed, adopting a double Thru-Reflect-Line calibration and allowing for accurate extracting of the interconnection response. The final interconnection to the MMICs has been realized using a via-less CPW to microstrip transition with high impedance transmission line S11 matching compensation. The simulated S11 and S22 are below -12 dB, Ohmic loss below 0.6 dB, radiation loss below 0.4 dB, and transmission line losses around 0.15 dB/mm.
Scanning Lens Phased Array Antennas
Analysis, design and demonstrations at millimeter and submillimeter wavelengths using leaky-wave feeds
Millimeter- and submillimeter wave applications, such as point-to-point wireless communications in beyond-5G scenarios, long-range automotive radars and astronomy and astrophysics science cases from space require antennas with high-gain beams that are steerable. At lower (microwave) frequencies, fully sampled phased arrays with thousands of elements have been demonstrated for this purpose. However, above roughly 100 GHz, integrated-circuit technology faces major bottlenecks in terms of size, power efficiency, thermal management and technological immaturity. Consequently, only integrated phased arrays with very few elements have been reported in the literature above 100 GHz. To still achieve the gain and enable beam scanning, mechanically actuated reflectors are now typically employed. However, such solutions are bulky, power-hungry and do not allow rapid beam steering. To overcome these limitations, we propose, analyze, design, fabricate and demonstrate a new antenna architecture in this thesis: the scanning lens phased array. The scanning lens phased array is a compact, low-power and very sparse array of integrated lens antennas that we demonstrate with scanning capabilities up to 25 degrees around broadside. A hybrid electro-mechanical approach to beam steering is employed: the array factor is scanned electronically and the element patterns are steered mechanically. The grating lobes that arise in the array factor due to the array’s sparsity are suppressed by the high directivity of the lens elements. This results in a clean, highgain beam towards the desired scan angle...
...
Millimeter- and submillimeter wave applications, such as point-to-point wireless communications in beyond-5G scenarios, long-range automotive radars and astronomy and astrophysics science cases from space require antennas with high-gain beams that are steerable. At lower (microwave) frequencies, fully sampled phased arrays with thousands of elements have been demonstrated for this purpose. However, above roughly 100 GHz, integrated-circuit technology faces major bottlenecks in terms of size, power efficiency, thermal management and technological immaturity. Consequently, only integrated phased arrays with very few elements have been reported in the literature above 100 GHz. To still achieve the gain and enable beam scanning, mechanically actuated reflectors are now typically employed. However, such solutions are bulky, power-hungry and do not allow rapid beam steering. To overcome these limitations, we propose, analyze, design, fabricate and demonstrate a new antenna architecture in this thesis: the scanning lens phased array. The scanning lens phased array is a compact, low-power and very sparse array of integrated lens antennas that we demonstrate with scanning capabilities up to 25 degrees around broadside. A hybrid electro-mechanical approach to beam steering is employed: the array factor is scanned electronically and the element patterns are steered mechanically. The grating lobes that arise in the array factor due to the array’s sparsity are suppressed by the high directivity of the lens elements. This results in a clean, highgain beam towards the desired scan angle...
Master thesis
(2021)
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N. van Rooijen, M. Alonso Del Pino, S. Bosma, N. Llombart Juan, M. Spirito, A. Neto
This thesis is concerned with a first time demonstration of a high frequency scanning lens phased-array with dynamic steering. Such phased-array could provide the high gain, wide bandwidth, and steering capability that the next generation of wireless applications requires. The phased-array development was divided into three distinct parts. First, the electronic phase steering system was discussed and developed, and its stability was characterized over time. Results obtained over 24 hours indicated that the system would be stable to within 6° of high frequency output phase. The drifts in output amplitude remained to within 0.3dB. Next, the lens antenna elements were developed with a novel corrugated leaky wave feed that provides very high and broadband aperture efficiency. Antenna measurements have validated its ability to be a very aperture efficient radiator (>80%) with wide bandwidth (1:2). Scanning measurements have shown a 3dB scan loss at around 15°. Finally, the phase steering and antenna elements were combined into a 4×1 array concept. Its behaviour was simulated and indicated again good performance with wide bandwidth (1:2) and high directivity (31.5dBi). Simulated scan loss was approximately 3dB at 20°. The amplitude and phase errors resulted in a SLL standard deviation of 0.63dB. The array prototype is currently awaiting completion of fabrication by DEMO at the TU Delft.
...
This thesis is concerned with a first time demonstration of a high frequency scanning lens phased-array with dynamic steering. Such phased-array could provide the high gain, wide bandwidth, and steering capability that the next generation of wireless applications requires. The phased-array development was divided into three distinct parts. First, the electronic phase steering system was discussed and developed, and its stability was characterized over time. Results obtained over 24 hours indicated that the system would be stable to within 6° of high frequency output phase. The drifts in output amplitude remained to within 0.3dB. Next, the lens antenna elements were developed with a novel corrugated leaky wave feed that provides very high and broadband aperture efficiency. Antenna measurements have validated its ability to be a very aperture efficient radiator (>80%) with wide bandwidth (1:2). Scanning measurements have shown a 3dB scan loss at around 15°. Finally, the phase steering and antenna elements were combined into a 4×1 array concept. Its behaviour was simulated and indicated again good performance with wide bandwidth (1:2) and high directivity (31.5dBi). Simulated scan loss was approximately 3dB at 20°. The amplitude and phase errors resulted in a SLL standard deviation of 0.63dB. The array prototype is currently awaiting completion of fabrication by DEMO at the TU Delft.