Integrated RF Research Articles

A miniaturized low-loss absorptive bandpass filter using IPD technology

In this article, a highly miniaturized absorptive bandpass filter based on a novel topology is presented. The filter topology utilizes a resistor-loaded network to achieve absorptive characteristics while additional capacitive coupling between series resonators is introduced to enhance selectivity. The proposed filter with a center frequency of 2.5 GHz and a 3-dB bandwidth of 2800 MHz is implemented using a GaAs integrated passive device (IPD) technology, exhibiting a small die size (0.7 mm×1.13 mm), low loss in-band insertion loss (0.9 dB), high out-of-band rejection (8.8f0¿25 dB), and a wide low-reflection frequency range. The measurement results show good agreement with the simulations. These features show promising applications in highly integrated RF systems.

A Highly Integrated C-Band Feedback Resistor Transceiver Front-End Based on Inductive Resonance and Bandwidth Expansion Techniques.

This paper presents a highly integrated C-band RF transceiver front-end design consisting of two Single Pole Double Throw (SPDT) transmit/receive (T/R) switches, a Low Noise Amplifier (LNA), and a Power Amplifier (PA) for Ultra-Wideband (UWB) positioning system applications. When fabricated using a 0.25 μm GaAs pseudomorphic high electron mobility transistor (pHEMT) process, the switch is optimized for system isolation and stability using inductive resonance techniques. The transceiver front-end achieves overall bandwidth expansion as well as the flat noise in receive mode using the bandwidth expansion technique. The results show that the front-end modules (FEM) have a typical gain of 22 dB in transmit mode, 18 dB in receive mode, and 2 dB noise in the 4.5-8 GHz band, with a chip area of 1.56 × 1.46 mm2. Based on the available literature, it is known that the proposed circuit is the most highly integrated C-band RF transceiver front-end design for UWB applications in the same process.

An RF coil design to enable quintuple nuclear whole-brain MRI.

To bring metabolic imaging based on multi-NMR toward practical use from the RF hardware perspective. A highly integrated RF coil is designed for whole-brain MRI and MRS targeted to five nuclear species: 1 H, 19 F, 31 P, 23 Na, and 13 C. Dipole antennas and closely loaded local receiver loops are combined in this setup. High-quality in vivo scan results of 1 H, 31 P, 23 Na, and 13 C on healthy volunteers have been achieved. For 1 H, the transmit efficiency is 77% of a single-tuned commercial head coil (NOVA 8-transmit [Tx]/32-receive [Rx]; NOVA Medical, Wilmington, MA, USA). For 31 P, 110% SNR of a dual-tuned close-fit head-birdcage was achieved at the center of the subject, based on MR experiments on a phantom. For 31 P, 23 Na, and 13 C, bench measurements indicate SNR loss of 15%, 27%, and 30% compared with single-tuned conditions. 19 F performance has been proven to be similar to that of 1 H through bench tests and electromagnetic simulations. With this device, 1 H-based anatomic images that are expected to meet clinical requirements, as well as high-quality multi-NMR images and spectra, can be acquired within one scan session without hardware replacement or patient repositioning, enabling morphologic and metabolic MRI within acceptable scan time.

A hexagonal high-performance transformer balun based on TSV technology for W-band application

Balun has been widely used for microwave circuits for its balance properties. The development of highly integrated RF systems has put forward higher requirements for superior performance and miniaturization of the balun. A compact broadband millimeter wave (MMW) transformer balun based on through silicon via (TSV) technology is proposed in this letter. Compared with the traditional balun, the proposed balun impedance ratio is 4:1, and the use of hexagonal coil winding significantly reduces its area and improves its performance. It is shown that the proposed balun has a magnitude imbalance of 0.64dB and a phase imbalance of 2.5° at 81.5-93GHz. A return loss of greater than 15dB is obtained for the frequency band ranges from 82.1-88.6 GHz. Furthermore, the area of balun is only 0.201×0.29mm2 (0.2×0.29λg2).

Highly-Isolated RF Power and Information Receiving System Based on Dual-Band Dual-Circular-Polarized Shared-Aperture Antenna

A highly integrated RF power and information receiving system is proposed in this paper. The system consists of an antenna, a rectifier, and an information receiving module. The information receiving module acts as part of the dc load. To realize high integration, a dual-band, dual-circular-polarized shared- aperture antenna is implemented. The antenna consists of a left-circular-polarized element operating at 2.4-GHz band, and a high-gain, right-circular-polarized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> array operating at 5.8-GHz band. The lower-frequency antenna is for communication, while the higher-frequency one is for power transmission. All the elements share the same aperture, and the radiator of lower- frequency antenna acts as the reflector of higher-frequency elements. Accordingly, a class-F rectifier that matches the higher- frequency array is designed and verified, and a system-level demonstration is implemented. Owing to the high isolation on frequency splitting and polarization diversity, the baseband signal can be successfully demodulated under a 30-dB input-power-level difference at two frequency bands. The base-band information can be displayed by an ink screen. The received RF power can be effectively rectified and power the data-processing modules.

Highly Energy-Efficient Metaconductor-Based Integrated RF Passives: Metaconductor-Based RF Passives

Human beings are naturally mobile and crave freedom. But, for many years, we were leashed to our office desks/homes to make a long-distance phone call. Finally, in 1973, the first-ever cellular phone call was made by Motorola engineer Dr. Martin Cooper using a handmade prototype device that weighed almost 2.5 lb. As Greek philosopher Heraclitus said, “Change is the only constant,” and over the past 50 years, cellular phone technology has undergone a drastic makeover where we drifted from a 2.5-lb cellular phone to a 0.4-lb smartphone (an iPhone 13), from typewriters to digital systems like desktops and laptops, and from paper maps to GPS for navigation. Similarly, as shown in <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1</xref> , our journey in wireless mobile communications started with 1G with analog data transmission and a data rate at ∼2.4 Kb/s to a full-fledged and operating 4G at a maximum data rate of 1 Gb/s.

Green and Highly Efficient MIMO Transceiver System for 5G Heterogenous Networks

The paper presents the general requirements and an exemplary design of the RF front-end system that in today&#x2019;s handset is a key consumer of power. The design is required to minimize the carbon footprint in mobile handsets devices, whilst facilitating cooperation, and providing the energy-efficient operation of multi-standards for 5G communications. It provides the basis of hardware solutions for RF front-end integration challenges and offers design features covering energy efficiency for power amplifiers (PAs), Internet of Things (IoT) controlled tunable filters and compact highly isolated multiple-input and multiple-output (MIMO) antennas. An optimum design requires synergetic collaboration between academic institutions and industry in order to satisfy the key requirements of sub-6 GHz energy-efficient 5G transceivers, incorporating energy efficiency, good linearity and the potential for low-cost manufacturing. A highly integrated RF transceiver was designed and implemented to transmit and receive a picture using compact MIMO antennas integrated with efficient tunable filters and high linearity PAs. The proposed system has achieved a bit error rate (BER) of less than 10&#x2013;10 at a data rate of 600 Mb/s with a wireless communication distance of more than 1 meter and power dissipation of 18&#x2013;20 mW using hybrid beamforming technology and 64-QAM modulation.

Integrated Wideband Chip-Scale RF Transceivers for Radar Sensing and UWB Communications: A Survey

With the rapid development of semiconductor technologies, the wideband transceiver is in the trend to be integrated on-chip with compact size and low power consumption. This survey investigates the integrated wideband chip-scale RF transceivers for radar applications including imaging, multimodal sensing, and recognition on gaits, where frequency modulated continuous wave (FMCW) radar sensors are investigated in detail. Besides radar sensing, integrated wideband RF transceivers for accurate localization and efficient communications with spectrum sharing are discussed, in which the integrated wideband transceiver techniques for ultra-wideband (UWB) communications are highlighted. The compact and efficient antenna designs for integrated wideband RF transceivers are discussed. Furthermore, leveraging the artificial intelligence (AI)-enhanced signal processing techniques, edge devices with energy-efficient integrated RF transceivers can ensure precise localization and realize versatile sensing to empower accurate health status monitoring, intelligent robots, gesture recognition, and enhanced communications. We envisioned the future integrated wideband RF transceiver development trends, where the promising tera-Hertz (THz) integrated transceiver techniques are discussed. Notably, the wideband integrated RF transceiver technique is promising to enable efficient, flexible, and seamless communications and sensing for the future-generation intelligent Internet of Everything (IoE) applications.

CMOS Channel-Selection Low-Noise Amplifier With High-$Q$ RF Band-Pass/Band-Rejection Filter for Highly Integrated RF Front-Ends

In this letter, a CMOS tunable channel-selection low-noise amplifier (LNA) employing a high- ${Q}$ RF band-pass (BP)/band-rejection (BR) filter is proposed for highly integrated RF front-ends in cellular applications. The proposed LNA implements a high- ${Q}$ RF BP/BR filter characteristic based on a four-path filter theory from a baseband polyphase filter and a low-pass filter. It also provides a high rejection ratio for close-in transmitter leakage signal and out-of-band blockers. Therefore, it compensates for the limited filtering performance of the CMOS duplexer and improves the blocker-tolerance and linearity of the receiver. The proposed LNA is implemented in 65-nm CMOS technology. It achieves a maximum voltage gain of 20.4 dB, a minimum NF of 3.24 dB, and a notch rejection ratio of more than 56.4 dB. It can also cover a low-band and a mid-band from 0.7 up to 2.2 GHz in cellular applications. It draws an average current of 13 mA from a supply voltage of 1.2 V and has an active area of 0.62 mm2.

A Dual-Band CMOS Tunable Duplexer Employing a Switchable Autotransformer for Highly Integrated RF Front Ends

A dual-band CMOS duplexer employing a switchable autotransformer is proposed for highly integrated RF front ends in mobile phones. Because on-chip switches are used to change the length of the autotransformer, the inductance is sized for two different frequency ranges. It is designed to support both low-band (LB) mode from 0.7 to 0.9 GHz and mid-band (MB) mode from 1.7 to 2.0 GHz for cellular applications. With different inductances for LB and MB modes, transmitter (TX)-to-receiver (RX) isolation is achieved by using two separate balance networks for LB and MB. The duplexer is implemented in a 65 nm CMOS process. In LB mode, TX and RX insertion losses (ILs) are less than 4.3 dB, while TX-to-RX isolation is more than 50 dB. In MB mode, TX IL and RX IL are less than 4.5 dB, while TX-to-RX isolation is more than 50 dB. The proposed duplexer proves feasible structure to cover both LB and MB frequency ranges in cellular 3G/4G applications.

Contact-Less Near-Field Test of Active Integrated RF Phased Array Antennas

Future RF transceivers are expected to integrate the entire system, from baseband to antenna. Many emerging applications use beam forming, which necessitates RF phased arrays and multiple antennas integrated on the same die. This integration presents a challenge in testing the entire system including antennas. The electromagnetic signal output is combined in the air and no longer can be separated by physically connecting to the test equipment. Testing each element in isolation does not exercise the interaction between the elements and cannot characterize important parameters such as phase mismatch. Thus, systems with multiple integrated antennas need to be tested using wireless means. This paper presents a novel contact-less near-field test method for measuring the gain and phase mismatch of RF phased array antennas. The proposed method is based on using a known good die (KGD) receiver phased array antenna to capture the combined EM output of the transmitter antenna as the device under test (DUT). The mathematical model of mutual impedances and signal propagation is presented for a 16-element phased array to determine both gain and phase mismatches. The feasibility of the method is shown using hardware measurement. The accuracy of the method under process variations and imperfections in the test set-up, including noise and error in test set-up dimensions, is further investigated through electromagnetic (EM) simulations of a coplanar patch antenna array of sixteen elements.

A Hybrid Transformer-Based CMOS Duplexer With a Single-Ended Notch-Filtered LNA for Highly Integrated Tunable RF Front-Ends

A hybrid transformer-based CMOS tunable duplexer with a single-ended blocker-tolerant low-noise amplifier (LNA) is proposed for a highly integrated reconfigurable RF front-end architecture. The proposed LNA adopts $Q$ -enhanced $LC$ notch filter at the source of the cascode device and $LC$ bandpass filter at the load. It improves the blocker tolerance and linearity of the receiver by rejecting unwanted out-of-band blockers and transmitter (TX) leakage signals. The duplexer with the notch-filtered LNA was fabricated in a 65-nm CMOS process. It has a voltage gain of 24.2 dB from the antenna to the LNA output with 28-dB notch filtering, cascaded noise figure of 6.4 dB, TX insertion loss of 3.8 dB, and IIP3FD of 52.4 dBm. It can also cover a mid-band range from 1.6 to 2.2 GHz in cellular applications. It draws an average current of 8 mA from a supply voltage of 1.2 V and has an active area of 1.19 mm2.

A 3D System-in-Package for RF Applications

Abstract A novel 3D packaging technology of substrate-based platform – double side module is introduced in this paper. This technology is capable of integrating RF front-end module with the advantage of package size reduction, excellent warpage control, and enhanced reliability. System in Package allows system designers to differentiate their products from others by integrating more functions to meet markets' requirement. It can also reduce the complexity of HW design while meeting their device / system requirements. The RF SiP is inherently heterogeneous integrated, for the foundry technologies of the dice inside could include digital CMOS, RF CMOS, III-V, piezoelectric, and other. In the era of 5G, new frequency bands of connected devices and denser component population have led to a demand for aggressive size reduction of RF FEM packaging solutions with good reliabilities and thermal management. The highly integrated 5G (under 6GHz) modem and RF FEM structure are crucial for modern premium tier smart phones' success, and are always a big challenge in the packaging industry due to its highly requirement of performance and manufacture yield.

Radiation tolerant RF-LDMOS transistors, integrated into a 0.[formula omitted] SiGe-BICMOS technology

Mixed signal on-chip solutions for space applications and high energy physics experiments require high voltage RF-LDMOS transistors with sufficient ruggedness against ionizing radiation and single event burnout. We report on a novel hardening by design approach for radiation tolerant integrated RF NLDMOS transistors confirmed by single event burn out (SEB) and total ionizing dose (TID) radiation tests. In order to substantially decrease TID induced leakage currents the shallow trench isolation (STI) of MOS transistors was replaced by narrow junction isolated regions. For a significant increase of the SEB onset voltage a cascode arrangement consisting of an isolated NMOS and NLDMOS was chosen. The floating NMOS-drain/NLDMOS-source node in the cascode arrangement is always reverse biased which efficiently avoids a turn-on of the parasitic npn bipolar transistor. The rad-hard isolated NMOS/NLDMOS cascode features a breakdown voltage BVDS > 50 V, a maximum cut off frequency fT= 5 GHz and a maximum oscillation frequency fMAX= 14 GHz. In comparison with standard NLDMOS transistors the isolated NMOS/NLDMOS cascode device shows an increase of the SEB onset voltage from 14V to 30V at a linear energy transfer LET of 67.7 MeVcm2/mg and a negligible increase of source drain leakage currents up to a TID of 1.5 Mrad after irradiation with a 60Co source.

An Integrated RF and Ambient Magnetic Field Approach for Indoor Positioning

A new technology for indoor positioning is proposed in this paper by applying combined RFID (Radio Frequency ID) / IRID (Infrared ID) and spatial fluctuations of the ambient magnetic field. Due to the presence of interior reinforced concrete construction, furniture, electronics and other indoor subjects, the distribution of the magnetic field intensity is fluctuated. Based on the spatial fluctuations, a particle filter algorithm can be employed to locate the indoor target. However, the computation power required for positioning in a large area could be very high because of the complexity of the application of the particle filter. Similar patterns of magnetic field in large area could also result in wrong location. Because of the short and tunable radiating range of the RF signal and the short response time of identification signal, the target may be positioned within a certain range by using RFID. Therefore, RFID/IRID positioning technique is introduced to approximate the position of the target and then particle filter is applied for precise positioning in the range of RFID/IRID signals. This can effectively reduce the number of required particles to carry out the particle filter algorithm, thereby reduce the amount of computation power, reduce the response time of the positioning and improve the accuracy of the estimated target position.

Integrating the Front End: A Highly Integrated RF Front End for High-SHF Wide-Band Massive MIMO in 5G

Fifth-generation (5G) mobile communications will need to accommodate huge traffic demands in the near future. Massive multipleinput/multiple-output (MIMO) technology utilizing hundreds of antenna elements has drawn attention as a key antenna configuration for envisioned 5G applications. Realizing the massive MIMO concept of active phased-array antennas (APAAs) for 5G will require small-size, low-power-consumption, and highly accurate phase control over the wide-band frequency range, which poses significant challenges for the RF front end. This article describes prototyped highly integrated RF front ends for high super-high-frequency (SHF) wide-band massive MIMO in 5G.

Dual-Polarized Small Base Station Antenna Integrated RF Module Applicable to Various Cell Environments for Next-Generation Mobile Communication Service

Dual-Polarized Small Base Station Antenna Integrated RF Module Applicable to Various Cell Environments for Next-Generation Mobile Communication Service

A Compact V-Band Planar Gap-Coupled $4\times 1$ Antenna Array: Improved Design and Analysis

In this paper, a broadband 60-GHz millimeter-wave $4\times 1$ microstrip patch antenna array using the gap-coupled technique is presented and analyzed. In order to meet the challenging requirement of reduced size related to this kind of technique, and facilitate the integration with other integrated passive or active devices, the proposed antenna array has been designed on a thin ceramic substrate ( $\varepsilon _{r} = 9.9 $ and $h = 127~\mu \text{m}$ ), using an miniature hybrid microwave integrated circuits (MHMIC) fabrication process. The proposed structure is based on a modified shape of a gap-coupled patch element with curved radiating edges. For further analysis, the performances of the latter in terms of impedance bandwidth, gain, and radiation efficiency were investigated and compared with a conventional structure of a rectangular gap-coupled patch antenna. The obtained results clearly show that the proposed gap-coupled array structure provides an improved bandwidth (7%) and an enhanced gain (10.7 dB), while maintaining a reduced size (5.2 mm $\times9.5$ mm). All these benefits make it an attractive candidate for the future integrated millimeter-wave RF front-end circuits; it can, however, be connected directly to various MHMIC passive circuits, or active devices through using the wire bonding technology, on a standard thin-film alumina substrate.

Passing the Plateau of Productivity: Development of RFSOI Technologies on HR Silicon Substrates for Reconfigurable Wireless Solutions

Products designed with RFSOI on HR silicon for the cellular handset industry are being deployed in large volumes by the leading RF FE providers. These consist of highly integrated RF power switches, RF tuners, and other types of RF circuit blocks. The technologies are available in several different foundries, and the volumes are running in the tens of thousands of wafers per month. The drive for improved linearity needed for LTE 4G systems, in particular CA, will continue to push these technologies to improve their respective figures of merit for continuous leadership in the RF FE. RFSOI on HR silicon is the leading switching technology in handsets today and is poised to continue its dominance for the next decade.

Highly integrated CMOS RF SPDT switch with ESD and unit cell optimisation in MCM

Presented is the performance of a highly integrated RF single-pole double-throw (SPDT) switch fabricated in a 0.18 µm bulk CMOS process and housed in a low-cost laminated multi-chip module (MCM-L) package. A switch controller is also implemented and consumes ∼40 µA from a 3.4 V supply. The switch, based upon the 1.8 V thin-oxide devices with resistive body-floating and unit cell layout optimisation techniques, achieves an insertion loss of 0.52/0.78 dB at 0.9/2.45 GHz, respectively. TX-to-RX isolation of > 29 dB and return loss of > 15 dB are achieved at these frequencies. The measured IP1dB of 21.7/21.2 dBm and IIP3 of 38.3/37.4 dBm are accomplished at 0.9/2.45 GHz, respectively. Finally, the switch achieves a RF electrostatic discharge (ESD) rating of 4 kV for the ± 2 kV human body model and 500 V for the ± 200 V machine model.