Wide RF Bandwidth Research Articles

Nucleation control of high crystal quality heteroepitaxial Sc0.4Al0.6N grown by molecular beam epitaxy

High ScN fraction ScxAl1−xN has promise in important application areas including wide bandwidth RF resonators and filters, and ferroelectric devices such as non-volatile memory, but demands high crystal quality. In this work, the role of the nucleation layer (NL), ScxAl1−xN growth temperature, and strain management to preserve the wurtzite crystal structure are investigated to maximize both acoustoelectric and ferroelectric material properties for high ScN fraction ScxAl1−xN grown on SiC substrates. A 5 nm AlN nucleation layer reduces the x-ray diffraction 0002 reflection full width at half maximum (FWHM) for a Sc0.32Al0.68N film by almost a factor of 2, and reducing the growth temperature to 430 °C enables a Sc0.40Al0.60N film with a FWHM of 4100 arcsec (1.1°) while being only 150 nm thick. Grading the initial ScxAl1−xN layer from x = 0.32 to 0.40 suppresses the formation of rock-salt grain nucleation at the Sc0.40Al0.60N lower interface and reduces the anomalously oriented grain density by an order of magnitude. Increasing the total ScxAl1−xN growth thickness to 500 nm produces an average x = 0.39 ScxAl1−xN layer with a FWHM of 3190 arcsec (0.89°) and an anomalously oriented grain areal fill factor of 1.0%. These methods enable the lowest heteroepitaxial ScxAl1−xN FWHM reported for x ∼ 0.4, with layer thicknesses and defect densities appropriate for high frequency (>10 GHz) filter applications.

A Ka - to G-Band Detector With 5.5-GHz Video Bandwidth Using a Modified Traveling-Wave Structure in 65-nm CMOS Technology

A broadband envelope detector implemented in 65-nm CMOS process is proposed in this brief. The travelling-wave topology is used for broadband design. A novel structure is presented to achieve wide RF bandwidth and video bandwidth (VBW) of this detector. A 1490-mV/mW maximum responsivity is measured at 300 GHz. The measured VBW of the proposed detector is 5.5 GHz. This circuit exhibits a very wide RF fractional bandwidth (164%) among the detectors covering up to 300 GHz.

Wideband SiGe down-converter for millimeter-wave radio astronomy applications

A Q-band down-converter module with high conversion gain (CG) is presented for a wideband radio astronomy receiver. This down-converter module is designed on a silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) process (0.13 μm) to realize high CG, low LO power operation, and wideband frequency impedance matching for RF/LO/IF ports. The down-converter consists of a double-balanced Gilbert mixing core with on-chip RF/LO transformer baluns, an IF buffer, and bandpass filter. The performance of the down converter is largely dependent on the passive components and signal line interconnection. The design of all passive structures is analyzed and optimized with FEM simulations for a high-quality factor to minimize losses and parasitic effects. This module achieves 8 dB of CG at a low LO power of −6 dBm over a wide RF bandwidth from 28 to 56 GHz and IF bandwidth from 6 to 18 GHz. It demonstrates LO-to-IF/LO-to-RF/RF-to-IF isolations > dB / 40 dB/35 dB, respectively. The critical FEM simulation is described in the design of this high-density SiGe HBT RF circuit. The measured performance confirms the simulation results. The module meets the original design requirements of the DVA-2 Q-band receiver.

Regenerative terahertz quantum detectors

Because of the ultrafast and photon-driven nature of the transport in their active region, we demonstrate that quantum cascade lasers can be operated as resonantly amplified terahertz detectors with wide RF bandwidth. Tunable responsivities up to 50 V/W and noise equivalent powers down to 100 pW/Hz1/2 are demonstrated at 4.7 THz. Constant peak responsivities with respect to the detector temperature are observed up to 80 K. Thanks to the ≈ps intersub-band lifetime, electrical bandwidths larger than 20 GHz can be obtained, allowing the detection of optical beatnotes from quantum cascade THz frequency combs.

480-GHz Sensor With Subharmonic Mixer and Integrated Transducer in a 130-nm SiGe BiCMOS Technology

A 480-GHz sensor consists of signal stimulus and the transducer element as well as a subharmonic mixer in a 130-nm SiGe BiCMOS technology is reported. It features a mixer-first architecture based on down-conversion subharmonic mixer, an local oscillator (LO) chain at 240-GHz using a frequency doubler with variable-gain characterization, and a 480-GHz RF chain, making the fully integrated 480-GHz receiver possible. In a frequency range of 210-270 GHz at a maximum of 1.5-V supply offset, the LO chain has a 14-dB power-level variation, comprising with a 120-GHz frequency quadrupler, a power amplifier, and a variable frequency doubler. The proposed subharmonic receiver is driven by the RF and LO chain with a multiplier factor of 16 and 8, respectively. In this way, 480-GHz signal is generated, fed through the transducer, and hetero-mixed at subharmonic mixer. The measured output power difference is adjustable over 8 dB. Along with the intermediate frequency (IF) bandwidth of 20 GHz, the wide RF bandwidth makes it suitable for submillimetre-wave receiver-based dielectric spectroscopy applications. The chip occupies an area of 2.2 mm 2 and consumes 290 mW.

High two-signal dynamic range and accurate frequency measurement for close frequency separation wideband digital receiver using adaptive gain control and adaptive thresholding

In electronic-warfare (EW) receiver applications, real-time measurement of the radar signals' carrier frequencies is mandatory and considered to be one of the most important radar parameters. Accurate frequency detection can be used to sort and deinterleave signals in a dense signal environment where multiple signals arrive simultaneously presenting severe problems unless they can be differentiated appropriately. Researchers and engineers are actively looking for new algorithms for high resolution wideband receivers with easier implementation. This paper presents an adaptive gain control and dynamic thresholding wideband digital receiver to accurately detect two simultaneous high dynamic range signals, even when their signal frequencies are very close. The proposed fast Fourier transform (FFT) based receiver examines incoming signal characteristics and provides real-time accomplishment of these tasks, by way of using an adaptive gain-control amplifier, a squarer, two analog-to-digital converters, and two FFT's. The wideband receiver offers high probability of intercept over wide instantaneous RF bandwidths, high dynamic ranges and sensitivity. Two simultaneous signal accommodations and their characteristics are provided to demonstrate the improvements over presently used receivers in this field.

An Innovative Joint-Injection Mixer With Broadband If and RF for Advanced Heterodyne Receivers of Millimeter-Wave Astronomy

An innovative mixing unit of the proposed mixer named joint-injection-mixer (JIM) features both wide IF and RF bandwidths (BWs) for next-generation advanced heterodyne receivers of millimeter-wave astronomy. This proposed mixer demonstrates an RF frequency range from 60 to 148 GHz and an IF frequency range from dc to 36 GHz. The dc power consumption of the JIM mixer is 2 mW with LO driving power of 0 dBm. All the measured results are under 0-dBm LO power. The conversion gain (CG) of the JIM mixer is from −8 to −14 dB. The JIM mixer in this work is implemented for fundamental mixing as downconversion. By utilizing the proposed modified Marchand balun with ultrabroad BW, the LO-to-RF isolation of the JIM mixer achieves better than 40 dB from 60 to 140 GHz. The fabricated process for the JIM mixer is the 40-nm CMOS process. The chip sizes, excluding and including pads, are 0.144 and 0.22 mm2, respectively. The proposed JIM mixer features the state-of-the-art mixer with the widest IF BW compared with all the prior works. Compared with the present capability of world-leading receivers for radio astronomy, the 36-GHz IF BW of the mixer in this work can construct a next-generation receiver for astronomy to provide received data rate by at least three times.

A 210–284-GHz I–Q Receiver With On-Chip VCO and Divider Chain

A 240-GHz direct conversion I–Q receiver with 74-GHz RF bandwidth is reported. It features a mixer-first architecture with fundamental local oscillator (LO)-frequency Gilbert-cell downconversion mixers, variable-gain baseband amplifiers, and a 240-GHz LO source, making it the first fully integrated 240-GHz I–Q receiver. With a phase noise of −82 dBc/Hz at 1-MHz offset, the LO source has a 27-GHz tuning range and consists of a 120-GHz voltage-controlled oscillator (VCO), a frequency doubler, and a static divide-by-128 chain. The measured peak downconversion gain is 23 dB and is adjustable over 38 dB. Along with the IF bandwidth of 59 GHz, the wide RF bandwidth makes it suitable for both high data-rate communication and emerging quantum computing applications. The chip occupies an area of 1.837 mm2 and consumes 859 mW.

Mixing It Up: A Double-Balanced Mixer with Wide RF and IF Bandwidth

This article presents the design details of a wide-band, high-dynamic-range passive gallium arsenide (GaAs) mixer submitted for the Student Design Competition (SDC) held during the IEEE Microwave Theory and Techniques Society (MTT-S) 2017 International Microwave Symposium in Honolulu, Hawaii, this past May. The target of our research was to achieve a wide-band mixer with high dynamic range and zero power consumption. The "High-Dynamic-Range Mixer" SDC was sponsored by Technical Coordination Committee MTT-22.

A Fully Integrated 240-GHz Direct-Conversion Quadrature Transmitter and Receiver Chipset in SiGe Technology

This paper presents a fully integrated direct-conversion quadrature transmitter and receiver chipset at 240 GHz. It is implemented in a 0.13- $\mu{\hbox{m}}$ SiGe bipolar-CMOS technology. A wideband frequency multiplier ( $\times$ 16) based local-oscillator (LO) signal source and a wideband on-chip antenna designed to be used with an external replaceable silicon lens makes this chipset suited for applications requiring fixed and tunable LO. The chipset is packaged in a low-cost FR4 printed circuit board resulting in a complete solution with compact form-factor. At 236 GHz, the effective-isotropic-radiated-power is 21.86 dBm and the minimum single-sideband noise figure is 15 dB. The usable RF bandwidth for this chipset is 65 GHz and the 6-dB bandwidth is 17 GHz. At the system level, we demonstrate a high data-rate communication system where an external modem is operated in its two IF-bandwidth modes (250 MHz and 1 GHz). For the quadrature phase-shift keying modulation scheme, the measured data rate is 2.73 Gb/s (modem 1-GHz IF) with bit-error rate of ${\hbox{10}}^{-9}$ for a 15-cm link. The estimated data rate over the 17-GHz RF bandwidth is, hence, 23.025 Gb/s. Also, higher order modulation schemes like 16 quadrature amplitude modulation (QAM) with a data rate of 0.677 Gb/s and 64-QAM with a data rate of 1.0154 Gb/s (modem 250-MHz IF) is demonstrated. A second application demonstrator is presented where the wide tunable RF bandwidth of the chipset is used for material characterization. It is used to characterize an FR4 material (DE104) over the 215–260-GHz range.

Discrete Implementation and Linearization of a New Polar Modulator-Based Mixerless Wireless Transmitter Suitable for High Reconfigurability

A novel polar modulator-based transmitter architecture that uses an analog RF variable gain amplifier (VGA) and an analog phase shifter is proposed and implemented using discrete elements. This architecture translates the baseband phase signal to RF without using mixers and quadrature up-converter circuits. Accordingly, spurs and distortions that are typically associated with the mixers are absent over a wide frequency band. As such, no filtering is needed at the output of the proposed transmitter. The absence of RF band pass filter provides wider RF bandwidth which would make the transmitter design reconfigurable and more suitable for integration. The proposed transmitter architecture has unusual signal distortion effects due to amplitude and phase nonlinearity in the VGA and the phase shifter. Indeed, this distortion consists not only in amplitude-to-amplitude (AM/AM) and amplitude-to-phase (AM/PM) distortions, but also includes phase-to-amplitude (PM/AM) and phase-to-phase (PM/PM) distortion. Hence, a new behavioral model using augmented complex memory polynomial is proposed to mitigate these complex nonlinear effects. The performance of the linearized transmitter is tested using long-term evolution (LTE) signals and the signal quality is assessed in terms of error vector magnitude (EVM). The measured EVM of the LTE signal of 1.4 MHz bandwidth at the output of the transmitter improved from 9.82% to 0.43% using digital predistortion technique. The measured adjacent channel leakage-power ratio (ACLR) of the proposed transmitter is 59 dBc.

Compensation of spectral and RF errors in swept-source OCT for high extinction complex demodulation.

We provide a framework for compensating errors within passive optical quadrature demodulation circuits used in swept-source optical coherence tomography (OCT). Quadrature demodulation allows for detection of both the real and imaginary components of an interference fringe, and this information separates signals from positive and negative depth spaces. To achieve a high extinction (∼60 dB) between these positive and negative signals, the demodulation error must be less than 0.1% in amplitude and phase. It is difficult to construct a system that achieves this low error across the wide spectral and RF bandwidths of high-speed swept-source systems. In a prior work, post-processing methods for removing residual spectral errors were described. Here, we identify the importance of a second class of errors originating in the RF domain, and present a comprehensive framework for compensating both spectral and RF errors. Using this framework, extinctions >60 dB are demonstrated. A stability analysis shows that calibration parameters associated with RF errors are accurate for many days, while those associated with spectral errors must be updated prior to each imaging session. Empirical procedures to derive both RF and spectral calibration parameters simultaneously and to update spectral calibration parameters are presented. These algorithms provide the basis for using passive optical quadrature demodulation circuits with high speed and wide-bandwidth swept-source OCT systems.

Korean VLBI Network Receiver Optics for Simultaneous Multifrequency Observation: Evaluation

ABSTRACTWe have developed a new millimeter wave receiver system with input optics that support simultaneous observations in four bands of 22, 43, 86, and 129 GHz to facilitate calibrating tropospheric phase fluctuations for millimeter-wave VLBI observations. In order to make simultaneous observations in four bands pointing at the same position in sky, it is crucial that errors among the beams from any misalignments should be kept small. After doing the beam alignment in the laboratory, on-site test observations were carried out so as to evaluate the performance. The result is that the beam centers of the four bands with reference to the 86 GHz beam center were aligned within 2″ over most of the elevation range of the Korean VLBI Network (KVN) 21 m telescope. Measured telescope aperture efficiencies including the multiband receiver optics are 65% at 22 GHz, 62% at 43 GHz, 57% at 86 GHz, and 38% at 129 GHz. Through this novel optics covering wide RF bandwidth effectively, we can simultaneously observe the SiO maser transitions at 43, 86, and 129 GHz and in addition the water maser line at 22 GHz.

해양용 DGPS 구조개선을 위한 RSIM 설계에 관한 연구

현재 운영되고 있는 해양용 DGPS 시스템은 하드웨어 RSIM 방식으로서 DGPS 구조개선시 고려해야 할 위성항법시스템의 다원화와 미래 해양 사용자의 최소 요구성능을 만족시킬 수 있는 기술 적용에 효율적이지 못하다는 문제가 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 소프트웨어 RSIM 방식으로 해양용 DGPS 시스템을 구조개선하는 방안을 연구한다. 이를 위해 본 논문은 해양용 DGPS 시스템에 적합한 소프트웨어 RSIM 방식을 제안하고, 제안한 방법의 기술적 타당성 분석을 위하여 광대역폭, 높은 표본화 주파수, 데이터 고속전송 사양을 갖는 RF 모듈과 DSP 모듈을 제작하며, 이를 이용하여 제안한 방법을 적용한 해양용 DGPS 시스템을 구현한다. 그리고 신호처리 소요시간 분석을 통하여 개인용 컴퓨터 환경에서 제안한 소프트웨어 RSIM 방식이 실시간으로 운영됨에 문제가 없음을 보인다. 마지막으로 본 논문은 제안한 방법으로 설계된 DGPS 시스템의 보정정보 정확도가 RTCM 221-2006-SC104-STD을 통해 규정된 국제기구 요구성능을 만족시키고 있음을 확인한다. Hardware dedicated off-the-shelf maritime differential GPS RSIM lacks the open architecture to meet all the minimum maritime user requirements and to include future GNSS improvements after recapitalization. This paper carries out a study to replace existing hardware dedicated differential GPS RSIM with software differential GPS RSIM in order to make up the weak point of hardware dedicated off-the-shelf maritime differential GPS RSIM. In this paper, the architecture of software RSIM is proposed for maritime DGPS recapitalization. And the feasibility analysis of the proposed software differential GPS RSIM is performed as the first phase to realize the proposed architecture. For the feasibility analysis, the prototype RF module and DSP module are implemented with properties as wide RF bandwidth, high sampling frequency, and high speed transmission interface. This paper shows that the proposed architecture has the possibility of real time operation of software RSIM functionality onto the PC-based platform through the analysis of computation time. Finally, this paper verifies that the L1/L2 dual frequency software differential RSIM designed according to the proposed method satisfies the performance specifications set out in RTCM paper 221-2006-SC104-STD.

A fully packaged true time delay module for a K-band phased array antenna system demonstration

A 1-to-64 [6-bit(2/sup 6/)] optical true-time delay module is designed, fabricated, and packaged for squint-free beam steering in phased array antennas, providing linear time delays ranging from 0 to 443.03 ps. The phases versus RF frequencies are measured to verify that the time delay is independent of RF frequencies. The optical true-time delay module is integrated into a K-band (18-26.5 GHz) phased-array antenna system. Far-field patterns at different frequencies over the entire K-band are measured and compared with simulated results to verify the system's wide instantaneous RF bandwidth. The Q factor is measured to be 10.20 of the true-time delay optical link transmitting 2.5-Gb/s random digital signal.

Thinned stepped frequency waveforms to furnish existing radars with imaging capability

Introducing imaging capability to an existing radar, even if it is a high RF bandwidth radar, may be difficult, due to limitations on the IF bandwidth, limitations on the pulse repetition frequency and electromagnetic compatibility problems. This paper discusses the use of thinned stepped frequency waveforms, which enable the radar to switch between RF frequencies to provide a synthesized wide RF bandwidth, while the thinning may alleviate some of the constraints imposed on the radar. Random and periodic thinning are discussed in the first part of this paper. However, thinning may cause degradation in image quality, thus an additional technique-Sequence CLEAN deconvolution-is suggested. Sequence CLEAN is an iterative deconvolution algorithm, adopted from the field of radioastronomy, which is capable of resolving close targets in a dense environment, where the system response is heavily affected by high sidelobes.

Photonic mixers for wide bandwidth RF receiver applications

Optoelectronic mixers can exhibit a very wide bandwidth of operation with significantly reduced third-order intermodulation products. A 20 GHz bandwidth optoelectronic mixer has been constructed and characterized. The third-order intermodulation terms were demonstrated to be more than 70 dB below the IF output. The mixer was then incorporated into a simple superheterodyne receiver architecture, which was shown to have a tangential sensitivity of -66 dBm and a compressive dynamic range of 44 dB. System limitations and possible improvements are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Consideration of RF Parameters for PCM Telemetry Systems

Considerable differences of opinion have existed concerning the requirements for transmission of PCM information. Quite often, PCM has been accepted as a system inherently requiring wide RF bandwidths and correspondingly poor noise performance. This paper considers selections of RF parameters for PCM telemetry systems. It points out that if these parameters are correctly chosen, the bandwidths and sensitivity of a PCM system may be made comparable with those of other existing telemetry systems.