Kamil Yavuz Kapusuz

Provides society information that may include news, reviews or technical notes that should be of interest to practitioners and researchers.

Provides society information that may include news, reviews or technical notes that should be of interest to practitioners and researchers.

This article presents a 4-way transmitter (TX) array suitable for beamforming operation at D-band. The transmitter is implemented using zero-IF architecture with LO beamforming. The signal path comprises an I/Q baseband (BB) section, direct up-conversion, and a power amplifier chain, supporting a wideband operation from 118 to 147 GHz. A 5-stage 2-way power amplifier chain provides a saturation output power up to 11 dBm. The probing measurement results demonstrate up to 64 quadrature amplitude modulation (64QAM) [30 Gb/s at −25 dB rms-error vector magnitude (EVM)] and achieve a data rate of 56 Gb/s with a −17 dB rms-EVM at an output power of 3 dBm using 16QAM modulation. The LO chain contains a 14–16 GHz buffer, a cascade of two frequency triplers for LO generation at D-band using an external LO reference. A tunable matching network with 6-bit capacitor-band control is implemented in the buffer stage together with a polarity switch to achieve full range phase control. An efficient I/Q generation scheme is implemented by exploiting the last tripler before the I/Q mixer: two LC buffers after 1st tripler generates ±15° phase offset. This results into ±45° phase offset after the 2nd tripler. The benefits of our sub-harmonic I/Q generation are: 1) no I/Q hybrid operating in D-Band is needed; 2) the limited ±15° phase offset required allows an easy LC tuned buffer implementation with limited amplitude variation across phase range; and 3) this amplitude variation is removed by 2nd tripler and LO buffers that operate at saturation level. This LO beamforming scheme ensures a phase resolution of 0.1° in measurement. A single TX channel draws 232 mW from a 0.8 V supply and has an area of $1.17\times 0.3$ mm² in a 22 nm fully depleted silicon on insulator (FD-SOI) process. The 4-way beamformer IC has been flip-chip mounted on a low-cost 10-layer printed circuit board (PCB) and connected to a planar antenna array integrated at the backside of the PCB. The antennas are placed with 1.1 mm spacing and each antenna contains 4 aperture-coupled patch units to enhance the radiation pattern. The 4-way TX beamformer has been tested over-the-air (OTA) with a reference receiver achieving 24 Gb/s with −25 dB rms-EVM at 0.4 m distance using 5G NR waveforms.

A wideband 4×4 planar phased array, based on four hybrid series/corporate-fed 4×1 subarrays with an asymmetrically positioned wide-stripline stub, is proposed for next-generation D-band applications. Each subarray consists of a stripline power splitter and 180°phase shifter serving as a corporate feed for two co-optimized back-to-back series-fed arrays, each with two stripline-fed aperture-coupled stacked patch antennas. This hybrid feed approach minimizes the number of required feed layers, reducing both structural complexity and fabrication costs, while ensuring stable gain across a wide bandwidth. As a proof of concept, prototypes of a 4×1 subarray and a 4×4 array, with respective dimensions of 0.96×4.8 mm$^{2}$ and 3.8×4.8 mm$^{2}$, were fabricated using a standard any-layer high-density interconnect printed circuit board process for operation in the [120-150] GHz frequency band, demonstrating a 22% fractional bandwidth. The 4×1 and 4×4 arrays achieve peak gains of 10 dBi and 14.5 dBi, with total efficiencies of 58% and 55%, respectively, and support beam steering over $\pm$ 45°. Furthermore, a 5 Gbaud 16-QAM wireless communication link over 26 cm distance was successfully established using the 4×4 array, achieving an error vector magnitude of less than 8%. This validates the use of the proposed antenna array at three carrier frequencies, enabling a 60 Gbit/s aggregated data rate for future multi-carrier D-band applications.

The co-design, fabrication and characterization of an active D-band antenna array with large bandwidth for use in next-generation, high-speed wireless systems is presented. A silicon-germanium (SiGe) BiCMOS D-band power amplifier (PA) is compactly integrated on the backside of a printed-circuit-board (PCB)-based 4×1 antenna array with a vertical substrate-integrated-waveguide-based corporate feed network, minimizing its impact on the array's radiation pattern, while keeping the array width below $\lambda$/2. This co-design is performed by employing a tailored wirebonding process to minimize interconnect loss and by optimizing the antenna array's input impedance to maximize the PA's peak output power. The former is achieved by thinning the integrated circuit (IC) and embedding it into a milled cavity in the PCB carrier, thereby leveling the IC and PCB surfaces to minimize the bond wire length. To attain the latter, a grounded co-planar waveguide-to-substrate-integrated-waveguide transition is proposed to tailor the antenna input impedance and compensate for the remaining effects of the bond wires. After assembly, the active antenna array is characterized in terms of gain, bandwidth and equivalent isotropic radiated power (EIRP). The module features a peak combined gain of 26 dBi over a 3dB-gain bandwidth of 23GHz and a maximum EIRP of 22.8dBm with a 25GHz EIRP bandwidth.

The design of arbitrary-shaped planar phased arrays arranged on a triangular grid is explored through an innovative approach utilizing uniformly fed tiles of various sizes and shapes, guided by graph theory principles. To meet user-defined constraints on the number of transmit/receive (T/R) modules and radiation pattern power masks, tile size and shape optimization is achieved using a genetic algorithm (GA) with a novel initialization technique. This method enables the synthesis of tiled arrays with tiles of arbitrary size and shape, catering to both low/medium-sized arrays and larger, computationally complex arrays. The proposed approach is validated through a series of representative numerical examples, including both ideal and realistic array models. Full-wave simulations are performed to demonstrate the effectiveness of the method, even when accounting for non-ideal radiating elements, including the effects of mutual coupling, and deviations in tile beamforming network (BFN). Moreover, comparisons with alternative tiling architectures emphasize the advantages of arbitrary tileing for different polygonal apertures, surpassing the capabilities of traditional diamond and domino-tiling techniques.

This study proposes a novel high-performance, two-element camera-integrated antenna array for the [401-406] MHz medical device radio communications service (MedRadio) band. The array is designed for integration inside a capsule to establish a stable, high data-rate multiple-input multiple-output (MIMO) wireless communication link for wireless endoscopy. The compact antenna ($\pi \times$ 1.125 ×1.49 mm$^{3}$) uses stacked meandered resonators, nestled within an annular ring-shaped planar substrate, offering over 7 MHz bandwidth and 41 dB isolation. It achieves a 78 Mbps data rate over 1.6 m in muscle tissue with a specific absorption rate of 2 W/kg at 20 mW power. Measurements show an ECC below 0.001, diversity gain over 9.99 dB, and a channel capacity of 10 bps/Hz at 20 dB SNR. To the best of our knowledge, this is the first dual-camera-integrated MIMO antenna system for the [401-406] MHz MedRadio band tested in an implantable device.

A new method is proposed to synthesize arbitrary-tiled arrays fitting multiple, generally conflicting, requirements for multi-antenna systems operating beyond 100 GHz. The array structure is decomposed into subarrays of arbitrary size and shape whose locations and orientations are optimized considering a genetic algorithm-based (GA) search. A simple yet powerful representation of subarrayed planar array antennas is developed tailored to GA search which enables the synthesis of tiled arrays comprising subarrays of arbitrary size and shape. A set of representative numerical examples is reported to assess the effectiveness of the proposed synthesis approach in comparison with the state-of-the-art solutions.