Receiver Chain Research Articles

Design of a MMIC low‐noise amplifier in industrial gallium arsenide technology for E‐band 5G transceivers

AbstractThe technology, design procedure and measurements of an E‐band (71‐86 GHz) high performance gallium arsenide (GaAs) low‐noise amplifier (LNA) are presented. The latter provides a gain in excess of 20 dB, an average in‐band noise figure (NF) of 2.3 dB, absorbing 60 mW DC bias power. A European space‐qualified technology (OMMIC's GaAs 70 nm process) has been selected to demonstrate the feasibility of employing the proposed LNA for production‐ready wireless backhaul point‐to‐point communication systems. A possible installation scenario has been depicted, in order to verify the maximum distance at which TX and RX antennas can be placed and employing the proposed LNA as first amplifying stage of the receiver chain.

An Element-Matched Electromechanical <inline-formula> <tex-math notation="LaTeX">$\Delta\Sigma$ </tex-math> </inline-formula> ADC for Ultrasound Imaging

This paper presents a power- and area-efficient approach to digitizing the echo signals received by piezoelectric transducer elements, commonly used for ultrasound imaging. This technique utilizes such elements not only as sensors but also as the loop filter of an element-level $\Delta \Sigma $ analog to digital converter (ADC). The receiver chain is thus greatly simplified, yielding savings in area and power. Every ADC becomes small enough to fit underneath a $150\,\,\mu \mathrm {m} \times 150\,\,\mu \mathrm {m}$ transducer element, enabling simultaneous acquisition and digitization from all the elements in a 2-D array. This is especially valuable for miniature 3-D probes. Experimental results are reported for a prototype receiver chip with an array of $5 \times 4$ element-matched ADCs and a transducer array fabricated on top of the chip. Each ADC consumes 800 $\mu \mathrm {W}$ from a 1.8 V supply and achieves a SNR of 47 dB in a 75% bandwidth around a center frequency of 5 MHz.

Passive Compressive Device in an MIMO Configuration at Millimeter Waves

A passive compressive device (PCD), which works at millimeter waves, is proposed in this paper. In a passive manner, the device allows to compress the signals from multiple separate channels into a single or a reduced number of channels. This permits a simplification of the transmitter or receiver chains for radar imaging applications. The PCD is a 3-D cavity that ensures each channel to be decorrelated with each other. If the transfer functions are known, the compressed signals are decompressed in postprocessing. This paper proposes a suitable method to estimate simultaneously the transfer functions of the PCD. This is validated by measurements in a multiple-input-multiple-output (MIMO) configuration to produce a complex synthetic aperture radar image. Measurements revealed that the point spread function generated by the MIMO configuration with the use of the PCD leads to almost similar results, in terms of spatial resolution and sidelobe level ratio, as those of a single-input-multiple-output configuration (uniform amplitude), with a fewer receiving elements.

Wideband 240-GHz Transmitter and Receiver in BiCMOS Technology With 25-Gbit/s Data Rate

In this paper, a fully integrated wideband 240-GHz transceiver front-end, supporting BPSK modulation scheme, with on-chip antenna is demonstrated in SiGe:C BiCMOS technology with $f_{\text {T}}/f_{\text {max}}\,\,=$ 300/500 GHz and local backside etching option. Within the transmitter, the upconversion is provided by fundamental mixing using a modified Gilbert cell mixer driven by a multiplier-by-eight local oscillator (LO) chain. The transmitter achieves a 3-dB RF bandwidth of 35 GHz with a saturated output power of −0.8 dBm. The down converter is equipped with a mixer first architecture. The mixer is designed utilizing a transimpedance amplifier as load for enhanced noise and bandwidth performance. For dc-coupled receiver, two dc offset cancellation loops are implemented within the receiver chain. It achieves a 3-dB RF bandwidth of 55 GHz, minimum single-sideband noise figure (SSB NF) of 13.4 dB, and a gain of 32 dB with 25-dB gain control. A wideband on-chip double-folded dipole antenna and an on-board optical lens are utilized to demonstrate a wireless link achieving 20- and 25-Gb/s data rates at bit error rates (BERs) of $6.3 \times 10^{-6}$ and $2.2\times 10^{-4}$ , respectively, across a distance of 15 cm. The transmitter and receiver consume 375 and 575 mW, respectively, which correspond to power efficiencies of 15 pJ/bit for the transmitter and 23 pJ/bit for the receiver. They occupy a silicon area of 4.3 and 4.5 mm2, respectively.

Software-defined radio technology for GNSS scintillation analysis: bring Antarctica to the lab

Global navigation satellite systems (GNSSs) are widely used to support logistics, scientific operations, and to monitor the polar ionosphere indirectly, which is a region characterized by strong phase scintillation events that severely affect the quality and reliability of received signals. Professional commercial GNSS receivers are widely used for scintillation monitoring; on the contrary, custom-designed solutions based on data grabbers and software receivers constitute novelty. The latter enables a higher level of flexibility and configurability, which is important when working in remote and severe environments. We describe the scientific, technological, and logistical challenges of installing an ionospheric monitoring station in Antarctica, based on a multi-constellation and multi-frequency GNSS data grabber and a software-defined radio receiver. Having access to the full receiver chain and to intermediate signal processing stages allows a deep analysis of the impact of scintillation and, in turn, a better understanding of the physical phenomenon. The possibility to process high-resolution raw intermediate frequency samples of the signal enables not only the computation of scintillation indexes with the same quality as professional devices but also the design and test of innovative receiver architectures and algorithms. Furthermore, the record and replay approach offers the possibility to process in the lab the signals captured on site, with high fidelity level. It is like being in Antarctica again, but with an unlimited set of receivers and higher computational, storage, and bandwidth resources. The main advantages and disadvantages of this approach are analyzed. Examples of monitoring results are reported, confirming the monitoring capabilities, showing the good agreement with commercial receiver outputs and confirming the validity of post-processing and re-play operations.

A 1 to 32 GHz broadband multi-octave receiver for monolithic integrated vector network analyzers in SiGe technology

AbstractA multi-octave receiver chain is presented for the use in a monolithic integrated vector network analyzer. The receiver exhibits a very wide frequency range of 1–32 GHz, where the gain meets the 3 dB-criterion. The differential receiver consists of an ultra-wideband low noise amplifier, an active mixer and an output buffer and exhibits a maximum conversion gain (CG) of 16.6 dB. The main design goal is a very flat CG over five octaves, which eases calibration of the monolithic integrated vector network analyzer. To realize variable gain functionality, without losing much input matching, an extended gain control circuit with additional feedback branch is shown. For the maximum gain level, a matching better than −10 dB is achieved between 1–28 GHz, and up to 30.5 GHz the matching is better than −8.4 dB. For both, the input matching and the gain of the LNA, the influence of the fabrication tolerances are investigated. A second gain control is implemented to improve isolation. The measured isolations between RF-to-LO and LO-to-RF are better than 30 dB and 60 dB, respectively. The LO-to-IF isolation is better than 35 dB. The noise figure of the broadband receiver is between 4.6 and 5.8 dB for 4–32 GHz and the output referred 1-dB-compression-point varies from 0.1 to 4.3 dBm from 2–32 GHz. The receiver draws a current of max. 66 mA at 3.3 V.

Radio Frequency Modeling of Receive Coil Arrays for Magnetic Resonance Imaging

The numerical calculation of the signal-to-noise ratio (SNR) of magnetic resonance imaging (MRI) coil arrays is a powerful tool in the development of new coil arrays. The proposed method describes a complete model that allows the calculation of the absolute SNR values of arbitrary coil arrays, including receiver chain components. A new method for the SNR calculation of radio frequency receive coil arrays for MRI is presented, making use of their magnetic B 1 − transmit pattern and the S-parameters of the network. The S-parameters and B 1 − fields are extracted from an electromagnetic field solver and are post-processed using our developed model to provide absolute SNR values. The model includes a theory for describing the noise of all components in the receiver chain and the noise figure of a pre-amplifier by a simple passive two-port network. To validate the model, two- and four-element receive coil arrays are investigated. The SNR of the examined arrays is calculated and compared to measurement results using imaging of a saline water phantom in a 3 T scanner. The predicted values of the model are in good agreement with the measured values. The proposed method can be used to predict the absolute SNR for any receive coil array by calculating the transmit B 1 − pattern and the S-parameters of the network. Knowledge of the components of the receiver chain including pre-amplifiers leads to satisfactory results compared to measured values, which proves the method to be a useful tool in the development process of MRI receive coil arrays.

Implementing and Characterizing Real-Time Broadband RFI Excision System for the GMRT Wideband Backend

ABSTRACTThe Giant Metrewave Radio Telescope (GMRT) is being upgraded to increase the receiver sensitivity. This makes the receiver more susceptible to man-made Radio Frequency Interference (RFI). To improve the receiver performance in the presence of RFI, real-time RFI excision (filtering) is incorporated in the GMRT wideband backend (GWB). The RFI filtering system is implemented on FPGA (Field Programmable Gate Array) and CPU (Central Processing Unit)–GPU (Graphics Processing Unit) platforms to detect and remove broadband and narrowband RFI, respectively. The RFI is detected using a threshold-based technique where the threshold is computed using Median Absolute Deviation (MAD) estimator. The filtering is carried out by replacing the RFI samples by either noise samples or constant value or threshold. This paper describes the status of the real-time broadband RFI excision system in the wideband receiver chain of the upgraded GMRT. The methodology for carrying out various tests to demonstrate the performance of broadband RFI excision at the system level and on the radio astronomical imaging experiments is also described.

Digital Suppression of Transmitter Leakage in FDD RF Transceivers: Aliasing Elimination and Model Selection

The transmitter (TX)-induced interference due to power amplifier nonlinearities poses severe desensitization problems to the receiver chain in frequency-division duplexing transceivers. Due to nonlinear signal process involved, a high sampling rate is normally required in the existing digital suppression approaches, which can result in high cost and high power consumption in wideband systems. In this paper, a new digital suppression model is proposed to cancel the TX leakage at baseband with a low sampling rate. The cancellation model is based on the modified decomposed vector rotation model. With the addition of cross-term products, the enhanced model is capable of eliminating the aliasing effect arising from the reduced sampling rate. Theoretical analysis of aliasing elimination is presented, and the algorithm is subsequently verified by both simulation and experiment results, confirming the effectiveness and feasibility of the proposed cancellation technique for TX leakage suppression. Compared with conventional solutions, the new approach uses much less hardware resource and consumes much lower power while achieving comparable performance.

A Compact In-Line Waveguide-to-Microstrip Transition in the Q-Band for Radio Astronomy Applications

A microstrip-to-waveguide transition has been realized for radio astronomy applications, designed to operate in the Q-band (33–50 GHz). As part of an array radio frequency (RF) receiver, the main requirement of such a transition is the reduction of transverse space occupation for the integration in the entire receiver chain, so an in-line configuration has been developed. Moreover, the high frequency band implies that an easy fabrication is a critical requirement if a good match between the two guiding structures is to be obtained in the desired band (with a relative bandwidth of 40%). The combination of CAD software and an optimization tool allows the device to achieve a good return loss over the entire band.

Joint Interference Mitigation and Data Recovery for Massive Carrier Aggregation via Non-Linear Compressive Sensing

Due to the demand for higher throughput, there is need for aggregating more carriers to serve one user equipment. Massive carrier aggregation (MCA) may help as it aggregates a large number of potentially non-contiguous carriers spanning a wide bandwidth. However, implementing MCA brings challenges to the design of the receiver and corresponding data recovery algorithms. For example, if we assign a separate receiver chain for each carrier, the number of receiver chains will be large, which imposes a huge cost. If we use a single receiver chain for all non-contiguous carriers, an expensive high rate analog-to-digital converter (ADC) is required to sample the entire span of the carriers. To reduce the cost, we propose a receiver architecture that employs only one receiver chain with a non-uniform ADC, whose sampling rate is much smaller than the Nyquist rate, and a low cost power amplifier with small dynamic range. Under such architecture, the received signal suffers from non-linear distortion and interference, and the resulting data recovery is a challenging non-linear compressive sensing problem. We propose an algorithm to jointly mitigate the interference and recover the data, which is proved to have theoretical performance guarantees and verified advantageous over baselines in simulations.

Third-order Single-bit Sigma Delta modulator structure for an RF reception chain for a LTE network

Third-order Single-bit Sigma Delta modulator structure for an RF reception chain for a LTE network

A Low Power Impedance Transparent Receiver with Linearity Enhancement Technique for IoT Applications

A low power receiver with impedance transparent RF front end is presented. By using the 4‐path passive mixer and the active feedback of LNA, the baseband impedance profile is further transferred to receiver input. While a LO‐defined input matching is formed by RF front end, the linearity of entire receiver chain is improved. Furthermore, derivative superposition technique is employed to cancel the distortion of the CMOS LNA. A 3rd‐order active‐RC filter is designed with current‐efficient feedforward compensated OTA. And a digital‐to‐time converter (DTC) assisted fractional‐N all‐digital phase‐locked loop (ADPLL) is codesigned with receiver to meet the IoT requirements. The presented receiver is fabricated in 55 nm CMOS technology with an active area of 2.3 mm2 and power consumption of 20 mW. Measurement results show that the receiver achieves 5.3 dB NF with 78 dB gain from 0.6 to 1 GHz, the RX out‐of‐band IIP3 is +8 dBm, and in‐band IIP3 is −10 dBm, and the ADPLL achieves −94 dBc/Hz in‐band PN and −120.5 dBc/Hz at 1 MHz offset.

A CMOS Ku-band receiver chain for phased array system

A CMOS Ku-band receiver chain for phased array system

Estimating the sensitivity and linearity requirements of an OTH radar receiving system

A desirable goal for an over-the-horizon radar (OTHR) receiver chain is to avoid degradation of available signal to noise ratio over unused channels within a nominated band of interest. If there is a design requirement for the receiver to perform instantaneously wideband, this can present a significant challenge as the dynamic range of signals within the high frequency (HF) band in the form of large broadcast signals, by way of contrast to the very low spectral densities characterizing cosmic noise, can easily exceed the linear range of components in a typical receiver chain. In narrowband systems, this has been handled in various ways by constraining the bandwidth impinging on sensitive downstream components, with a highly linear bandpass filter, or custom mixer and filter. Even in narrowband systems care must be taken to ensure that the receive chain internal noise and nonlinear products do not significantly impact at operational frequencies of interest. More recently, with the advent of direct digital receivers (DDRx) based around high speed high dynamic range analogue to digital converters (ADCs), a desire to operate OTHR with wide open front ends (WOFE) has emerged. In a WOFE DDRx there is no bandpass filtering within the operational range of the receiver. The principle is to enable multiple simultaneous functions using the large radar receive array, e.g. the usual narrowband radar with a complementary wideband frequency management support (FMS) system [1]. This goal demands simultaneous access across the full spectrum and therefore constrains the filtering solution and increases the technical demand on the receiver components. As discussed in Barnes et. al. [2] the general application of Commercial-Off-The-Shelf (COTS) DDRx to attempt WOFE at HF will generally result in some level of system imposed performance limiting. The use of customized, dynamically adaptive front-end gain stages, including the use of equalization, where the gain is a tailored function of frequency, can allow the receiver to approach a satisfactory WOFE solution in some applications, e.g. the spectral environment evaluation and recording [2] receiver.

Ionospheric Response to 22–23 June 2015 Storm as Investigated Using Ground‐Based Ionosondes and GPS Receivers Over India

AbstractIn this paper, we present response of equatorial and low‐latitude ionosphere to 22/23 June 2015 geomagnetic storm using a chain of ground‐based ionosondes located at Tirunelveli (8.73°N,77.70°E; geomagnetic latitude: 0.32°N), Hyderabad (17.36°N, 78.47°E; geomagnetic latitude: 8.76°N), and Allahabad (25.45°N, 81.85°E; geomagnetic latitude: 16.5°N) along with a chain of GPS receivers. Uniqueness of this storm is that in contrast to the equatorial plasma bubbles that were detected in the European sector, we see suppression of plasma bubbles in the Indian sector. The observations suggest that westward penetration electric field during local midnight caused abrupt decrease of virtual height (h'F (km)) to ~200 km and suppressed plasma bubbles due to undershielding. Later, the layer increased to 500 km simultaneously due to overshielding effect. On 23 June, we observed negative storm in the Northern Hemisphere while positive storm in the Southern Hemisphere. In addition, absence of equatorial Es layers at Tirunelveli and presence of F3 layer at Tirunelveli/Hyderabad seem to be associated with equatorial electrojet (EEJ)/counter electrojet (CEJ) variations. However, on 24 June, we observed strong negative storm effects at Allahabad/Hyderabad, while positive storm effect at Tirunelveli. Simultaneous enhancement of h'F (km) at all three ionosonde stations at 20:30 UT on 23 June during recovery phase suggest eastward disturbance dynamo (DD) electric field that caused presunrise spread F at Hyderabad/Allahabad but void of spread F at Tirunelveli suggesting its midlatitude origin. Periodogram analysis of foF2 and h'F (km) in the present analysis suggest the presence of shorter periods (~< 2 h) associated with prompt penetration (PP) electric fields while larger periods (>2 h) associated with DD electric field/winds.

Hybrid SI cancellation for single‐antenna full‐duplex radios

A hybrid self-interference (SI) cancellation scheme, composed of a two-tap analogue canceller and a digital multi-path SI canceller, is proposed for single-antenna full-duplex radios. The analogue canceller mitigates the two strongest components of the SI to prevent saturating the receiver. The digital canceller deploys an auxiliary receiver chain to capture the RF-transmitted signal to mitigate the residual multi-path SI signal. As the proposed scheme uses the RF-transmitted signal as reference, the transceiver impairments such as power amplifier non-linearities and phase noise are suppressed along with the SI. Experiments have validated the effectiveness of the proposed scheme on a 20 MHz long-term evolution signal of +20 dBm power.

Do Patients Who Receive Medium Chain Trigyceride Enteral Tube Feeds Post Intestinal/Liver and Intestinal Transplant Demonstrate Better Weight Gain and Growth than Those Changed to a Standard Tube Feed?

Introduction: There is little published literature on nutrition post intestinal transplant despite it being integral to its management. Current practice at Birmingham Children's Hospital (BCH) is to use a tube feed containing 50% Medium Chain Triglycerides (MCT). At 8–12 weeks Long Chain Triglycerides (LCT) are introduced into the feed, as the intestinal mucosa has recovered, LCT is transported via transected lymphatics into the peritoneal cavity, and absorption is presumed to take place via the peritoneal lymphatics. [1] A group of patients remained on MCT feeds as the time to change feeds coincided with illness. A review of published data and protocols concludes that the established intestinal graft in a healthy state absorbs key nutrients adequately to wean off parenteral nutrition, and although there is varying practice different approaches can equally lead to success.[2] Due to a lack of data, review of our patient’s growth on MCT and LCT is warranted to determine if a change in practice is advantageous. Method: This study is a retrospective dietetic note review of patients who had a small bowel or combined bowel transplant in the past 10 years at BCH. The group was divided into patients remaining on MCT feeds at 12 months’ post-transplant versus those changed to an LCT feed at 3 months. Weight and height data was collected at 3, 6 and 12 months’ post-transplant in addition to feed type. Exclusions are those who died within the 12 months following transplant. Results:FigureFigure95 children had a small bowel or combined transplant in the past 10 years. 26 patients were excluded as they died within 12 months, 17 as notes in archive. 16 remained on MCT feeds at 12 months (31%) whereas 36 were changed to contain LCT at 12 weeks per current protocol (69%). Despite small numbers differences in the median weight gain and growth between the two groups are seen with the MCT group having superior results. Conclusion: The patients who remained on MCT feeds demonstrate better weight gain and growth than those who were changed to an LCT feed. These results are being analyzed to see if they are statistically significant. In all patients the volume of feed given was to meet requirements, and all were supplemented with sodium to a total of 6mmol/100mls. Based on the findings patients may benefit from MCT feeds for longer, post-transplant, and data should be analyzed over a longer period. Carla Lloyd.

High-performance cryogenic fractal 180° hybrid power divider with integrated directional coupler

A 180° hybrid and a directional coupler to be employed in the P-band cryogenic receiver of the Sardinia Radio Telescope are proposed in this work. An in-depth study of the issues related to the use of microwave components for cryogenic radio astronomy receivers is carried out to select the best suited technology and configuration. As a result, a planar fractal 180° hybrid configuration available in the literature has been optimized aiming to increase the operating bandwidth in order to comply with the design specifications of the application at hand. A coupled lines directional coupler with weak coupling and high isolation, used to calibrate the receiver chain, is cascaded to the 180° hybrid and realized in the same layout. The final device, consisting of the 180° hybrid and the directional coupler, has been manufactured and tested at the cryogenic temperature of 20 K, showing a good agreement between experimental results and predicted performance.

A Wideband Digital Back-End for the Upgraded GMRT

Traditionally, back-ends for radio telescopes have been built using a hardware-based approach with ASICs, FPGAs, etc. With advancements in processing power of CPUs, software-based systems have emerged as an alternative option, which has received additional impetus with the advent of GPU-based computing. We present here the design of a hybrid system combining the best of FPGAs, CPUs and GPUs, to implement a next generation back-end for the upgraded GMRT. This back-end can process 400 MHz bandwidth signals from 32 dual-polarized antennas, for both interferometry and beamformer applications, including narrowband spectral line modes for the interferometer, incoherent array and phased array mode of operations for the beamfomer, and also a voltage mode attached to a real-time coherent dedispersion system for the beamformer. We describe in detail the design and architecture of this system, including the novel features and capabilities. We also present sample results from the system that validate its performance in conjunction with the entire receiver chain of the upgraded GMRT.