Front-end Module Research Articles

Dual-Passband SAW Filter Based on a 32°YX-LN/SiO2/SiC Multilayered Substrate.

To meet the demands of highly integrated and miniaturized radio frequency front-end (RFFE) modules, multi-passband filters which support multi-channel compounding come to the foreground. In this work, we proposed a new design of a dual-passband surface acoustic wave (SAW) filter based on a 32°YX-LiNbO3 (LN)/SiO2/SiC multilayered structure. The filter is of a standalone ladder topology and comprises dual-mode resonators, in which the shear horizontal (SH) mode and high-order SH mode are simultaneously excited through electrode thickness modulation. The impact of electrode thickness on the performance of the dual-mode resonator was systematically investigated by the finite element method (FEM), and resonators were prepared and verified the simulation results. The electromechanical coupling coefficients (K2) of the SH modes are 15.1% and 17.0%, while the maximum Bode-Q (Qmax) values are 150 and 247, respectively, for the fabricated resonators with wavelengths of 1 μm and 1.1 μm. In terms of the high-order SH modes in these resonators, the K2 values are 9.8% and 8.4%, and Qmax values are 190 and 262, respectively. The fabricated dual-band filter shows the center frequencies (fc) of 3065 MHz and 4808 MHz as two bands, with 3-dB fractional bandwidths (FBW) of 5.1% and 5.9%, respectively. Such a dual-band SAW filter based on a conventional ladder topology is meaningful in terms of its compact layout and diminished area occupancy. This work provides a promising avenue to constitute a high-performance dual-passband SAW filter for sub-6 GHz RF application.

Investigation and Research of High-Performance RF MEMS Switches for Use in the 5G RF Front-End Modules

In this article, based on the developed methodology, the stages of designing two designs of high-performance radio-frequency single-pole single-throw microelectromechanical switches are investigated. These radio-frequency microelectromechanical switches are designed to operate at a central resonant frequency of 3.6 GHz and 3.4 GHz, respectively, as well as to work both in mobile communication devices and in the design of the architecture of 5G mobile networks, in particular in arrays of integrated antennas and radio-frequency interface modules. The manufacture and study of two designed structures are researched. For the first manufactured experimental sample in the open state the insertion loss is no more than -0.69 dB and the reflection loss is -28.35 dB, and in the closed state the isolation value is at least -54.77 dB at a central resonant frequency of 3.6 GHz. For the second in the open state the value of the insertion loss is no more than -0.67 dB and the reflection loss is -20.7 dB, and in the closed state the isolation value is not less than -52.13 dB at the central resonant frequency of 3.4 GHz. Both manufactured experimental samples are characterized by high linearity, as well as a small value of contact resistance in the closed state.

Low-Cost Impedance Camera for Cell Distribution Monitoring.

Electrical impedance spectroscopy (EIS) is widely recognized as a powerful tool in biomedical research. For example, it allows detection and monitoring of diseases, measuring of cell density in bioreactors, and characterizing the permeability of tight junctions in barrier-forming tissue models. However, with single-channel measurement systems, only integral information is obtained without spatial resolution. Here we present a low-cost multichannel impedance measurement set-up capable of mapping cell distributions in a fluidic environment by using a microelectrode array (MEA) realized in 4-level printed circuit board (PCB) technology including layers for shielding, interconnections, and microelectrodes. The array of 8 × 8 gold microelectrode pairs was connected to home-built electric circuitry consisting of commercial components such as programmable multiplexers and an analog front-end module which allows the acquisition and processing of electrical impedances. For a proof-of-concept, the MEA was wetted in a 3D printed reservoir into which yeast cells were locally injected. Impedance maps were recorded at 200 kHz which correlate well with the optical images showing the yeast cell distribution in the reservoir. Blurring from parasitic currents slightly disturbing the impedance maps could be eliminated by deconvolution using an experimentally determined point spread function. The MEA of the impedance camera can in future be further miniaturized and integrated into cell cultivation and perfusion systems such as organ on chip devices to augment or even replace light microscopic monitoring of cell monolayer confluence and integrity during the cultivation in incubation chambers.

Perturbation analysis of second-order nonlinearity and its effectiveness for radiofrequency bulk acoustic wave devices

Suppression of nonlinear signal generation in radiofrequency (RF) surface and bulk acoustic wave devices is one of the most important subjects for the RF front-end modules of recent cellular handsets. In particular, issues with second-order nonlinear products of bulk acoustic waves are well known. In this work, we succeeded in extracting the dominant parameters for second-order nonlinear analysis proposed by Hashimoto et al. [Joint Conf. European Frequency and Time Forum and IEEE Freq. Cont. Symp., 2017, p. 538] and verified that it is applicable in a wide frequency range and also effective for film bulk acoustic resonator (FBAR) device design. Combining the extracted nonlinear coefficients on the perturbation analysis by driving near the fundamental frequency (f0) and half resonant frequency (1/2f0) of the FBAR could reproduce second-order nonlinear characteristics in a wide frequency range. It was also confirmed that the proposed simulations are in good agreement with measurement results for various types of resonators and FBAR filters.

Low-Power and High-Precision Readout Circuit Design for Micro-Electromechanical Systems (MEMS) Acceleration Sensors

MEMS acceleration sensors are widely used in Internet of Things, electronic machinery, aerospace and other fields with outstanding advantages such as small size, high reliability, intelligence and high integration. Traditional MEMS acceleration sensors limit their applications due to high-power consumption and low-precision; the standby time and service life are being increased in order to study the low-power and high-precision MEMS acceleration sensor readout, this paper adopts the Fully Differential Switched Capacitor-Variable Gain Amplifier (FDSC-VGA) instead of the traditional high-power Capacitance-to-Voltage Converter (CVC-VGA), Sample-and-Hold Circuit (S&H) and Anti-Aliasing Filter (AAF) as front-end modules. At the same time, a high-precision four-phase non-crossover clock is designed to precisely control the timing switch, thus effectively reducing the power consumption of the MEMS acceleration sensor readout circuit; then, the overall readout circuit is simulated and verified by Dong Bu HiTek 0.18 μm process. The results show that the error rate of the output voltage of FDSC-VGA is reduced from 8.03% to 0.88% compared with the conventional readout circuit, and the noise power consumption of MEMS acceleration sensor readout circuit can be reduced by 65%.

Antenna Array on Glass Interposer for 6G Wireless Communications

This paper demonstrates integrated packaging solutions for antenna components in D-band by using glass-based package. We design sub-terahertz patch antennas at 140 GHz frequency band using HFSS simulation, and form arrays of patch antennas for 6G (sub-THz) wireless communication applications. The patch antennas and feeding networks are implemented using microstrip structures on the top of the interposer, with ground planes beneath. Build-up layers of polymer dry films are laminated on a glass core for multi-layer copper metallization, and copper structures are patterned on the polymer layers. For precise fabrication of the antenna and feeding structures in package, we implement the semi-additive patterning process to deposit the copper structures. Adequate measurement methods are applied to address difficulties in D-band antenna measurements. By forming patch antenna arrays, we obtain 10 dBi gain using a 4-element linear array and 14 dBi gain using a 4-by-4 2-D array. The bandwidths achieved for these arrays are 7% (10 GHz) and 5% (7 GHz), respectively, based on return loss measurements. Overall, the measurement results present good match to simulation. Antenna structures on glass substrates demonstrated in this paper represent the basic building block for heterogeneous integration of D-band front-end module in glass-based packages.

Design of Front-End Receiver and Matrix for 2–18 GHz with a Searching and Tracking Function for an ELINT System

In this paper, we describe the design and fabrication of a front-end receiver and matrix modules for 2−18 GHz with high gain, good phase matching characteristics, and reliability; this was accomplished by applying a chip-and-wire process using a bare-type monolithic microwave integrated circuit (MMIC) device. To compensate for the mismatch among many sub-modules, a front-end module, matrix module, and built-in test module suitable for sub-band frequency characteristics were designed and applied to the direct receiver. The matrix box used a high-pass filter to remove unwanted low frequencies and a 4-way divider to distribute single input BIT signals. The broadband receiver module had two paths: a phase path and an amplitude path. Phase- and amplitude-matched radio frequency semi-rigid cables of different lengths were used to connect to the internal sub-modules of the matrix receiver. The main RF line was a dielectric substrate, RT/Duroid 5880, with a relative dielectric constant of 2.2 and a dielectric thickness of 0.127 mm. The sizes of the front-end receiver and matrix box were 137 mm × 120 mm × 31 mm and 250 mm × 238 mm × 138 mm, respectively. In the wideband frequency receiver module, the gain was 22.99 dB at mid-band (frequency 2−6 GHz) with a return loss of about 14.76 dB. Th e gain was 23.25 dB at a high band (frequency 6−18 GHz), having a return loss of about 11.63 dB. The peak values of phase matching among the channels for 2–6 GHz were ±3.30°, and the peak values of phase matching among the channels for 6–18 GHz were ±8.24°.

An Ultra-Compact Bidirectional Ka-Band Front-End Module With 3.8-dB NF and 13.5-dBm OP1 dB

This letter presents an ultra-compact bi-directional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$ </tex-math></inline-formula> -band front-end module (FEM) in 65-nm CMOS technology. In this design, the receiver (RX) path is stacked into the transmitter (TX) path by using a magnetic self-canceling technique, improving area efficiency greatly with negligible performance penalty. Furthermore, a three-inductor coupled resonator is elaborately designed to realize the functions of the balun and input–output matching network (MN) of the RX/TX simultaneously. The measurement results demonstrate that the proposed FEM achieves 18.2-dB peak gain with a 3.8-dB minimum noise figure (NF) in RX mode, and 26-dB peak gain with 13.5-dBm 1-dB compression output power (OP <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{1\,{\mathrm {dB}}}$ </tex-math></inline-formula> ) in TX mode. The core size of this proposed design is only 0.06 mm2 which is only 20%–50% of the size occupied in prior works.

Substrate Integrated Waveguide Multiband Bandpass Filters and Multiplexers: Current Status and Future Outlook

Multiband bandpass filters (BPFs) and multiplexers are essential front-end modules in the development of multifunction, multistandard, and multiband wireless communication, sensing, and positioning systems that are required in current and future intelligent electronics applications. In this paper, numerous implementation schemes and topologies of multiband BPFs and multiplexers, which have been proposed, studied, and developed so far, are holistically summarized and elaborated in terms of their merits and drawbacks. Subsequently, various technical approaches and diverse design methodologies based on substrate integrated waveguide (SIW) technology are thoroughly examined and reviewed with respect to technical features, electrical performances, and practical applications. Finally, future research and development directions and prospects of SIW multiband BPFs and multiplexers are briefly unraveled.

Temperature-Independent Current Dispersion in 0.15 μm AlGaN/GaN HEMTs for 5G Applications.

Thanks to high-current densities and cutoff frequencies, short-channel length AlGaN/GaN HEMTs are a promising technology solution for implementing RF power amplifiers in 5G front-end modules. These devices, however, might suffer from current collapse due to trapping effects, leading to compressed output power. Here, we investigate the trap dynamic response in 0.15 μm GaN HEMTs by means of pulsed I-V characterization and drain current transients (DCTs). Pulsed I-V curves reveal an almost absent gate-lag but significant current collapse when pulsing both gate and drain voltages. The thermally activated Arrhenius process (with EA ≈ 0.55 eV) observed during DCT measurements after a short trap-filling pulse (i.e., 1 μs) indicates that current collapse is induced by deep trap states associated with iron (Fe) doping present in the buffer. Interestingly, analogous DCT characterization carried out after a long trap-filling pulse (i.e., 100 s) revealed yet another process with time constants of about 1-2 s and which was approximately independent of temperature. We reproduced the experimentally observed results with two-dimensional device simulations by modeling the T-independent process as the charging of the interface between the passivation and the AlGaN barrier following electron injection from the gate.

A Millimeter-Wave GaN MMIC Front End Module with 5G NR Performance Verification

This paper proposes a millimeter-wave (mmWave) 5G front end module (FEM) based on multiple gallium nitride (GaN) monolithic microwave integrated circuits (MMICs) with 5G new radio (NR) performance verification. The proposed structure is configured by a wide band GaN single-pole double-throw (SPDT) switch MMIC, a GaN low-noise amplifier (LNA) MMIC, and a GaN power amplifier (PA) MMIC with the target operation band from 26.5 GHz to 29.5 GHz. The LNA and PA MMICs are designed with 150 nm GaN/SiC technology, and the SPDT MMIC is designed with 100 nm GaN/Si. The LNA MMIC shows the measured noise figure less than or equal to 2.52 dB within the operation band. The PA MMIC is based on a two-stage configuration and shows about 35 dBm measured saturated power with power-added efficiency better than 34% within the operation band. Also, the SPDT MMIC is based on an artificial transmission line configuration for wideband performance and shows that the measured insertion loss is less than 1.6 dB, and the measured isolation is higher than 25 dB within the operation band. Furthermore, all MMICs are integrated within a single carrier as an FEM and successfully verified by 5G NR test signals.

Power Amplifier and Low Noise Amplifier for WLAN Applications

WLAN applications operating at a frequency of 2.45 GHz are a frequently used communication method in transmission tools. The connection functions to send and receive data between access points and smart devices are also fulfilled by WLAN technology. Communication quality in data transfer gains importance for this technology at every stage. Front-end module structures are used to increase such quality affects directly the efficiency. Circuits including power amplifier (PA), low noise amplifier (LNA), antenna and filter are the most significant components compose front-end structures. In this study, PA and LNA using PW570 gain block &amp; BFP760 RF transistor circuit respectively are proposed. By means of the usage of the proposed circuits, there will be considerable improvements in data communication speed and area of coverage, which are among the WLAN performance factors.

An Overview of Indian Spoken Language Recognition from Machine Learning Perspective

Automatic spoken language identification (LID) is a very important research field in the era of multilingual voice-command-based human-computer interaction. A front-end LID module helps to improve the performance of many speech-based applications in the multilingual scenario. India is a populous country with diverse cultures and languages. The majority of the Indian population needs to use their respective native languages for verbal interaction with machines. Therefore, the development of efficient Indian spoken language recognition systems is useful for adapting smart technologies in every section of Indian society. The field of Indian LID has started gaining momentum since the early 2000s, mainly due to the development of several standard multilingual speech corpora for the Indian languages. Even though significant research progress has already been made in this field, to the best of our knowledge, there are not many attempts to analytically review them collectively. In this work, we have conducted one of the very first attempts to present a comprehensive review of the Indian spoken language recognition research field. In-depth analysis has been presented to emphasize the unique challenges of low-resource and mutual influences for developing LID systems in the Indian contexts. Several essential aspects of the Indian LID research, such as the detailed description of the available speech corpora, the major research contributions, including the earlier attempts based on statistical modeling to the recent approaches based on different neural network architectures, and the future research trends are discussed. This review work will help assess the state of the present Indian LID research by any active researcher or any research enthusiasts from related fields.

Demonstration system of the HGTD peripheral electronics boards for ATLAS phase II upgrade

Prior to the prototype of the HGTD peripheral electronics boards (PEB) for the ATLAS phase II upgrade during the HL-LHC, a demonstration system has been developed to verify some uncertain aspects and facilitate many related studies and tests. Benefiting from its modular design, the system can not only make it possible to replace malfunctioning chips but also be compatible with commercial chips when the key chips are not available. With two lpGBT chips and one VTRx+ deployed, the system can support up to 14 front-end modules, one downstream (2.56 Gbps) and two upstream (10.24 Gbps) optical links. In addition, a module emulator was designed to mimic the front-end modules in both dimension and functionality since real modules are still in development. With a FPGA-based board uFC as the DAQ board, the system was extensively tested and showed very good performance, in particular, the uplink and downlink paths were successfully established and the bit error rates of the data transmission are less than 1×10−14.

A 64-channel high-time resolution digital waveform sampling electronic system based on DRS4 for positron burst annihilation lifetime measurement

Measurements of the positron burst annihilation lifetime place high demand on the time discrimination of electronics. DRS4 chips based on switched capacitor array technology (SCA) are used to develop an electronic system with a total (2048 + 256)-channel sampling rate up to 5.12 GSPS, which can provide better time resolution and flexible data processing. The electronic system is modular in design and includes a front-end waveform sampling module (WSM) with 32 waveform sampling boards, each with 64 input channels plus 8 additional channels(one per DRS4 chip) for time calibaion, in addition to a back-end data processing module (DPM). The fan-out circuit integrated with the DPM will fan out the T0 signal in multiple stages at the time of positron burst generation and provide a common starting time and trigger signal for every DRS4 chip in the WSM. In this electronic system, the jitter of T0 after three-stage fan-out is 18 ps. After DC offset correction and time interval nonuniformity calibration, the coincidence time resolution with other channels is about 21 ps (σ). In addition, we correct the time difference of different channels of different chips, which is caused by different trace lengths of the multi-level fan-out T0 signal and the different fabrication processes. The electronic system is used to evaluate a 64-pixel detector module, and the time resolution of the detection module is measured to be 44 ps (σ).

A 245 GHz Real-Time Wideband Wireless Communication Link with 30 Gbps Data Rate

This paper presents a 245 GHz wireless communications system with a data rate of 30 Giga bits per second (Gbps) at a 1.2 m distance, which proves the potential for future high-speed communications beyond 5G technology. The system consists of low-complexity and real-time base-band modules to provide the high-speed wideband signal processing capability. Multi-channel base-band signals are combined and converted to 15.65 ± 6.25 GHz wideband intermediate frequency (IF) signals. A novel 245 GHz waveguide bandpass filter (BPF) with low loss and high selectivity is designed and applied to a terahertz (THz) front-end for image rejection and noise suppression. Configuration of the base-band, IF, and THz front-end modules is also given in detail. The 245 GHz wireless communication link is demonstrated over a distance of 1.2 m.

Readout Electronics of the Prototype Beam Monitor in the HIRFL-CSR External-Target Experiment

The External-target Experiment (CEE) at the Cooling Storage Ring of the Heavy-Ion Research Facility in Lanzhou (HIRFL-CSR) will be the first large-scale experiment in nuclear physics independently developed in China covering the GeV energy regime. The beam monitor located at the center front of the CEE accurately measures the position of the particles with a few tens of um accuracy in a non-interceptive way. This unique advantage significantly improves the accuracy of the particle track reconstructions. This beam monitor’s readout electronics consist of the Front-end module (FEM), Readout Control Module (RCM), and Clock Synchronization module (CSM). Twhe novel Topmetal series pixel sensors directly collect the ionized charge along the track of the ion beam while it passes through the gas in the beam monitor. Lab test proves that the readout electronics have an INL of less than 1%. In addition, the prototype beam monitor can measure the position of the 40Ar beam of 320 MeV/u with a resolution of ~6.9 μm. This paper will discuss the design, characterization, and test of the readout electronics.

Factor graph-based high-precision visual positioning for agricultural robots with fiducial markers

High-precision positioning of agricultural robots is the key to the automation of greenhouse agricultural production. We propose a visual positioning method by leveraging the fiducial markers and factor graph to achieve reliable performance. This method consists of two parts, a front-end module and a back-end module. First, fiducial markers are involved to the front-end module to tackle the problems of unstructured and insufficient features in the greenhouse environment. A tag detection algorithm AprilTag2 is used to identify markers and extract feature points for the positioning purpose. Second, to eliminate the adverse effects of camera motion, mechanical vibration, and environmental disturbance on the positioning accuracy, the back-end module considers the characteristics of robot motion and the constraint relationship of variables, and correspondingly designs a positioning model based on the factor graph. The model combines five factors for maximum a posteriori estimation and incremental optimization of the state of the robot in real time. Finally, the positioning experiment of the wheeled robot was carried out at the motion speed of 0.26 m/s, 0.39 m/s, and 0.52 m/s. The experimental results show that the average errors of positioning are 0.056 m, 0.065 m, and 0.081 m, respectively, and the standard deviations of the errors are lower than 0.05 m. The visual positioning method based on fiducial markers and factor graph outperforms the mainstream positioning techniques in terms of positioning accuracy and robustness, and meet the high-precision positioning requirements in complex agricultural fields.

A Neuro-Space Mapping Method for Harmonic Interference Prediction of SOIFET Radio Frequency Switches

With the rapid development of wireless communication, the requirements of high-integration and low-cost radio frequency (RF) front-end modules in mobile phones result in more usage of silicon-on-insulator field effect transistors (SOIFETs) for the manufacturing of RF switches. However, the nonlinear behavior of SOIFET switches in <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> -state always produces unwanted harmonics distortion interference when they are excited by a large signal. In this article, we simplify the well-known physics-based surface potential model to an interelectrode nonlinear capacitance (INC) model since it adequately describes the harmonic effects produced by the transistor. The INC model, referred to as the coarse model, cannot match the behavior of the real switch, since many parameters of the switch cannot be accurately determined. This article proposes a novel dynamic neuro-space mapping network model, referred to as the fine model, to optimize the INC model. The proposed model takes advantage of the high accuracy of the fine model and the fast speed of the coarse model. Ultimately, the proposed method can accurately predict the harmonics interference for SOIFET switches in the complex RF front-end environment and provides an intuitive guideline under the design stage to prevent EMI problems.

Analysis of Two-Piano Teaching Assistant Training Based on Neural Network Model Sound Sequence Recognition.

In today's society, with the gradual improve5ment of material living standards, people are also more in pursuit of their own spiritual enjoyment. The study of piano has gradually become a way for people to enrich their spiritual life, and more and more people attach importance to it. In the field of piano teaching, the two-piano method is a unique form of playing the piano. In order to solve the problem that the recognition accuracy of the sequence of two pianos is seriously reduced in the environment of noise and reverberation, this paper proposes an auxiliary training analysis system based on the neural network model. Firstly, in order to learn the nonlinear relationship between the sound order and the target task label from the massive data, a multitask preprocessing method combining speech enhancement and detection is used to supervise the deep neural network training. Then, convolutional neural network is used to construct the end-to-end recognition system, and the initial recognition results are checked and corrected by the phonological sequence model. Finally, the sequence recognition is carried out under the condition of noise, and the articulation is improved by speech enhancement front-end module, and then the sequence recognition model is used for recognition. Compared with traditional training methods, it is proved that our method is effective in improving the training efficiency and performance quality of players. At the same time, this method breaks through the limitation of traditional training method of double piano, creates a more scientific training means, and realizes the practice and application of artificial intelligence technology in the teaching of double piano.