Power dissipation minimization in RF front ends

Direct conversion receiver (DCR) architecture is a promising candidate in the radio frequency (RF) front end because of its low power consumption, low cost and ease of integration. However, flicker noise and direct current (DC) offset are large issues. Owing to the local oscillator (LO) frequency, which is half of the RF frequency, and the absence of a DC bias current that introduces no flicker noise, the subharmonic passive mixer (SHPM) core topology front end overcomes the shortcoming effectively. When more and more receivers (RX) and transmitters (TX) are integrated into one chip, the linearity of the receiver front end becomes a very important performer that handles the TX and RX feedthrough. Another reason for the requirement of good linearity is the massive electromagnetic interference that exists in the atmosphere. This paper presents a linearity-improved RF front end with a feedforward body bias (FBB) subharmonic mixer core topology that satisfies modern RF front end demands. A novel complementary derivative superposition (DS) method is presented in low noise amplifier (LNA) design to cancel both the third- and second-order nonlinearities. To the best knowledge of the authors, this is the first time FBB technology is used in the SHPM core to improve linearity. A Volterra series is introduced to provide an analytical formula for the FBB of the SHPM core. The design was fabricated in a 0.13 μm complementary metal oxide semiconductor (CMOS) process with a chip area of 750 μm × 1270 μm. At a 2.4 GHz working frequency, the measurement result shows a conversion gain of 36 dB, double side band (DSB) noise figure (NF) of 6.8 dB, third-order intermodulation intercept point (IIP3) of 2 dBm, LO–RF isolation of 90 dB and 0.8 mW DC offset with 14.4 mW power consumption at 1.2 V supply voltage. These results exhibit better LO–RF feedthrough and DC offset, good gain and NF, moderate IIP3 and the highest figure of merit compared to the state-of-the-art publications.

Rapidly growing demand for high data rates in wireless communication systems is the cause of the merging of Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) techniques. MIMO-OFDM technique needs Radio Frequency (RF) front end in each antenna, which is not effective for large dimensional antenna size. Therefore, RF front end on the receiver side will be simplified using a single RF technique based on the Electrically Steerable Parasitic Array Radiator (ESPAR) antenna. In real life, a channel cannot be ideal. Therefore, before the signal is transmitted, that signal must be coded to minimized errors when the data transmission process. Convolutional code is a coding technique that can detect and correct error bit (error control coding) and that it is expected to reduce the quantity of Bit Error Rate (BER). In this research, a simulation is designed to analyze single RF performance on the MIMO-OFDM system using Vertical Bell Laboratories Space-Time (VBLAST) detection for convolutional code encoder and Viterbi decoder. The result simulation shows that the channel estimation technique works well on the MIMO-OFDM system using single RF, which is shown in the magnitude and phase curves against the subcarrier index between the theory channel and the estimated channel are at almost the same points. VBLAST-ZF detector performance is shown in the BER curve against SNR, where the difference BER value for SNR value 10 dB between the theory channel and the estimated channel is 0.001499. Channel coding technique using convolutional code encoder and Viterbi decoder with a rate of ½ works well on the MIMO-OFDM system using single RF which is shown in the BER curve against SNR, where BER value with coding technique is smaller than BER value without coding technique.

A frequency-modulated ultrawideband (FM-UWB) hybrid transceiver, with a high system reuse ratio up to 90%, is fabricated in the 65-nm CMOS process for both short-range wireless communication and high-resolution radar ranging. The radio frequency (RF) front-ends (RFFEs) based on module stacking and current reuse achieve significant RF power savings of about 30% and 50% for the transmitter and the receiver (RX), respectively. The presented IF zero-crossing delay discrimination benefits a high radar resolution less than 1 cm. A multimode relaxation oscillator (OSC) for the reconfigured triangular subcarrier generation and a dual-path ring voltage-controlled oscillator (VCO) for the linear FM, stacked by a wideband push–pull power amplifier (PA), generate an FCC-compliant UWB signal. An active balun embedded low-noise amplifier (LNA) and two symmetric-detuning band-passed filters (BPFs) are stacked with the bandwidth extension to linearly demodulate the UWB FM signal. Experimental results show that the 3.75–4.25-GHz hybrid transceiver has an energy efficiency of 1.9 nJ/bit with an active area of 0.7 mm2 and a power dissipation of 1.9 mW and achieves the RX sensitivity of −71 dBm and the transmitted power of −14.1 dBm, with a bit error rate (BER) of 10−4 at a distance of 4 m under the data rate (DR) of 0.1–1.0 Mbps. The transceiver also achieves the noise figure (NF) of 4.8 dB and the phase noise of −78.6 dBc/Hz at 1-MHz offset frequency.

This paper discusses use of MEMS technologies in radio frequency (RF) frontend. First, configuration of RF front-end in current wireless communication systems is surveyed, and research trends of the flexible RF front-end and software defined radio (SDR) are discussed. Second, various RF tunable filters are introduced, and we discuss how high performances are expected by the use of tunable RF surface and bulk acoustic wave (SAW/BAW) filters provided that above mentioned key technologies are developed. Finally, our attempts for realization of tunable RF SAW/BAW filters are introduced.

Polarization-sensitive array (PSA) can sense satellite signals from multiple dimensions and separate signals from interference according to various characteristics. Hence, the use of PSA improves the interference rejection capability of the global navigation satellite system (GNSS). Whereas it also brings a significant increase in computational complexity as there are more dimensions of array signal processing. Therefore, it is urgent to seek a method to employ fewer radiofrequency (RF) front-ends and antennas while still achieving superior anti-interference performance. In this paper, we investigate the influence of PSA configuration on interference suppression performance and propose an RF front-end optimal selection scheme for reconfigurable anti-jamming PSA with application to GNSS. Combining adaptive array processing algorithm and RF front-end selection strategy, we formulate the expression of the effective carrier to noise ratio (CNR) to analyze the performance enhancement generated by PSA reconfiguration. An approach is presented to solve the upper bound of the effective CNR to plot the trade-off curve between performance and cost, which can guide the selection of the optimal number of RF front-ends. Then another method is used to acquire the layout of the chosen optimal RF front-ends that can maximize the effective CNR. Numerical results illustrate the effectiveness and high efficiency of the proposed PSA reconfiguration scheme.

To achieve better antenna performance and eventually radio localization in fifth and/or sixth generation (5G/6G) wireless systems, it requires massive antenna array-based radio frequency (RF) front ends, resulting in increased overall hardware and computational complexity. In this paper, we propose an electromagnetic (EM) lens focusing antenna, which is capable of providing improved antenna parameters with less complexity as compared to traditional without lens antenna. The proposed EM lens antenna array, where an EM lens, fabricated by a 3D printer, is combined with a microstrip patch antenna array, has an ability to focus the incoming signal on a small area/subset of the antenna array, after passing through the lens, as a function of the angle of arrival (AoA). Resultantly, with the same signal energy as without a lens, we have to process a subset of the antenna array, which eventually contributes to reducing the complexity of the overall RF front end. Furthermore, the performance of the antenna parameters is enhanced significantly. The measured results, i.e., gain and 3 dB beamwidth, are 15.4 dB and 31.5°, respectively, in the case when a single 4.2 GHz frequency patch antenna is combined with an EM lens, which are much improved as compared to the traditional without lens antenna. The improved antenna parameters and AoA-based focusing ability of the proposed 3D-printed lens antenna show that the location-based services for 5G and 6G systems can be achieved in a better way with less complexity.

Application of high-temperature superconducting small current limiting against over-current in low-noise amplifier electronic circuit

The quantum cellular automata (QCA) paradigm offers an ultra-low-power approach for realizing nanocomputing circuits at the molecular level, offering high parallelism capabilities. This study introduces a coplanar and energy-efficient implementation of the approximate binary discrete cosine transform (BinDCT) module using QCA technology. The proposed BinDCT module integrates various sequential and combinatorial submodules, including multiplexers (MUXs), demultiplexers (DeMUXs), parallel-in-parallel-out right-shift registers (PIPO-RSRs), ripple carry adders (RCAs), and ripple borrow subtractors (RBSs). Each submodule is systematically designed following the standard single-layer design principles, which are crucial for maximizing circuit performance, enhancing reliability, and minimizing power dissipation. Extensive simulations were conducted to validate the logic operation and energy dissipation of each submodule. The simulation results demonstrate a significant reduction in power dissipation- up to and an improvement in circuit area efficiency by compared to previous QCA implementations.

The RF front end is generally defined as everything between the antenna and the digital baseband system. For a receiver, it includes all the filters, low-noise amplifiers (LNAs), down-conversion mixers and demodulator needed to process the modulated signals received at the antenna into signals suitable for input into the baseband analog-to-digital converter (ADC), demodulate it and feed with a Transport Stream the Back End part of the system to decode the signal. For this reason, the RF front end is often called the RF-to-TS portion of a receiver. It turns out that this is the most important and critical part of the whole receiver aiming for its good or bad performance. This thesis researched the existing problems that degenerate the analog TV transmission quality; the digital TV tests realized by Mackenzie DTV laboratory comparing the digital TV transmission standards, ATSC, DVB-T and ISDB-T; the proposed and adopted model for the Brazilian Digital TV System; and a proposal of a Front End for the SBTVD that meets the requirements of the system with robustness and flexibility. The Front End was designed, assembled and tested in the DTV laboratory and in the field.

In this paper, a novel global interconnect low voltage differential signaling (LVDS) transmitter for network-on-chip (NOC) has been proposed to achieve less global interconnect delay and low power dissipation. The proposed interconnect with transmitter has been examined in two different conditions, without buffer and with buffer in between interconnect and also impact of feature size scaling has been analyzed. The performance has been analyzed for the NOC interconnect with $0.350 \mu \mathrm {m}$ and $0.180 \mu \mathrm {m}$ CMOS technology. On scaling the technology with $0.350 \mu \mathrm {m}$ to $0.180 \mu \mathrm {m}$, the results show 15.68% global interconnect delay reduce for transmitter without buffer (Model-I) in between interconnect and with buffer (Model-II) global interconnect delay reduction of 15.83%. A significant reduction in power dissipation is achieved by selecting a proper sizing of transistor and using differential signaling technique of the data transmission. The power dissipation in $0.350 \mu \mathrm {m}$ technology is $1.78 \mathrm {m}\mathrm {W}$ and $0.180 \mu \mathrm {m}$ technology is $2.1929 \mathrm {m}\mathrm {W}$, respectively, at data rate of 2.9 Gbps and 3.5 Gbps at different technology for two different models.

A compact very low loss onchip bandpass filter which suits the 5G radio frequency front end (RFFE) filtering requirements, is reported here. The proposed filter is modeled using $0.18 \mu\mathrm{m}$ CMOS Silicon substrate IPD technology. A series LC resonant onchip BPF structure is designed and simulated by combining a passive multilayer (ML) spiral inductor and a planar spiral capacitor in High Frequency Structural Simulator (HFSS) at component level. The filter showed a quality factor (Q) value of 7.3125 and a fractional bandwidth of 13% ( $340\times 240 \mu\mathrm{m}^{2},\quad 280\times 240 \mu\mathrm{m}^{2}$ and $480\times 240 \mu\mathrm{m}^{2}$ respectively. It had demonstrated with an excellent loss along with a narrow passband characteristics, still occupying very small onchip area. Hence, this compact resonator filter definitely suits the 5G front end filter applications. We simulated this filter by focusing around 3.5 GHz, as this spectral band is used in 4G and also being actively considered for several 5G trials and installations across several countries.

The idea of Global Positioning System (GPS)/Global Navigation Satellite System (GNSS) “spoofing,” or the ability to mislead a satellite navigation receiver into establishing a position or time fix which is incorrect, has been gaining attention as spoofing has become more sophisticated. Various techniques have been proposed to enable detection if a receiver is being spoofed – with varying degrees of success and computational complexity. In this paper, a monitor in the Radio Frequency (RF) front end using the automatic gain control (AGC) mechanism is outlined. It has low computational complexity and is an extremely powerful means to detect spoofing, making spoofing no more of a threat than the much less sophisticated radio frequency interference/jamming. The technique is validated using live testing. Copyright © 2012 Institute of Navigation.

This communication presents a compact quarter-mode substrate integrated waveguide (QMSIW) cavity-backed self-diplexing tunable antenna. An open-ended slot is used to split the circular half-mode SIW (HMSIW) cavity resonator into two QMSIW cavity resonators. A varactor diode-loaded stub is added with each QMSIW resonator to achieve miniaturization and resonant frequency tuning. The miniaturization and tunability technique is demonstrated in a stand-alone QMSIW resonator and also in a QMSIW based self-diplexing antenna. The antenna is simulated, optimized, and subjected to practical testing inside a rectangular device. The device is treated as a quasi-receiver/transmitter, which consists of electronic circuitry and the proposed antenna. The resonant frequencies can be independently tuned by changing the values of the varactor diodes connected with each resonator. The simulated and measured results confirm that the proposed antenna can be tuned from 3.77 to 4.59 and from 4.96 to 6.1 GHz in the lower and higher frequency bands, respectively. The isolation between the two resonators in both bands is always better than 21 dB. The measured gains vary from 4.85 to 5.87 and 4.87 to 6.5 dBi in the lower and higher frequency bands, respectively. The proposed design shows stable and unidirectional radiation patterns in all tuning cases in both bands. The proposed self-diplexing tunable antenna is a competitive choice in compact and spectral-efficient radio frequency (RF) front ends where tuning is necessary for the efficient use of the frequency spectrum.

Ground-satellite links for 6G networks face critical challenges, including severe path loss, tight size-weight-power limits, and congested spectrum, all of which significantly hinder the performance of traditional radio frequency (RF) front ends. This article introduces the Rydberg Atomic Quantum Receiver (RAQR) for onboard satellite systems, a millimetre-scale front end that converts radio fields to optical signals through atomic electromagnetically induced transparency. RAQR’s high sensitivity and high frequency selectivity have the potential to address link-budget, payload, and interference challenges while fitting within space constraints. Theoretically, a hybrid atomic–electronic design that is supported by a consistent signal model achieves spectral efficiency exceeding 6 bit/s/Hz, extends coverage by up to 1000 km, and improves sensing accuracy by two orders of magnitude relative to conventional RF receivers. The paper concludes with integration strategies, distributed-satellite concepts, and open research challenges for bringing RAQR-enabled satellite payloads into service.

Based on Digital Beamforming (DBF) technology, spaceborne SAR systems can achieve high-resolution and wide-swath (HRWS) imaging. When combined with reflector antennas, the DBF-SCORE (Digital Beamforming-SCan On REceive) system also features light weight and low cost, making it an important choice for spaceborne HRWS SAR. This paper firstly proposes an advanced Full-chain Real-time Internal Calibration (FRIC) scheme, where the calibration path covers the entire receive chain from the antenna feed port to the input port of the Analog-to-Digital Converter (ADC) and achieves high-precision internal calibration concurrently with data acquisition. Secondly, based on the L-band reflector antenna DBF-SCORE system architecture, the design of radio frequency (RF) front end, namely the Transmit-Receive-Calibration Module (TRCM), is carried out. We propose the implementation of azimuth encoding modulation of the calibration signal through periodic switch control within the TRCM. Subsequently, the calibration signal is extracted using waveform diversity technology and its Signal-to-Noise Ratio (SNR) is improved through azimuth coherent integration technology. In addition, a ground verification system is established using the TRCM to evaluate the comprehensive performance of transmitting, receiving, and real-time internal calibration. Experimental results verify the effectiveness of the FRIC scheme and provide valuable insights for future spaceborne DBF SAR systems.