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This paper provides an extensive analysis of the performance of a six-port based direct conversion receiver (SPR) in terms of signal quality, dynamic range, noise-figure, ports matching, isolation, bandwidth and cost. Calibration technique using multi-memory polynomials has been adopted in order to improve the signal quality of the six-port receive...
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... Then the modulated RF signal can be obtained after combining (6) and (9) ...
In this paper, a new method to design a digitally assisted and spurious-free direct carrier mixerless modulator based on the six-port correlator is proposed. The calibration of the modulator based on modified Cartesian memory polynomial (MCMP) is used to linearize and mitigate hardware impairment of the whole system. The modulation and the up conversion are performed by using the variable loads controlled by the differential in-phase and quadrature-phase baseband voltages together with common-mode voltages. The proposed MCMP is able to compensate for nonlinearity, frequency responses, residual carrier leakage, crosstalk between the in-phase and the quadrature-phase data. The proof-of-concept of digitally assisted mixerless modulator is developed and its performance is assessed at 2.6 GHz with modern communication signals. The error vector magnitudes between the input ideal baseband signals and the up-converted radio frequency signals are all between 2% and 4%. The residual carrier leakage, which remains present after imperfect suppression through hardware means, degrades the overall system performance and it can be suppressed completely by means of the proposed memory polynomial model.
... Time-Delay Neural Networks methods have been proposed to design the demodulator for the I /Q (in-phase and quadrature) signal recovery. This is in view of the fact that it features more advantages of wide frequency coverage, easy fabrication, zero intermediate frequency (IF) without mirror frequency suppression filter, passive circuit realization for easy integration, and low cost than the conventional low IF receiver or the superheterodyne receiver [2]. According to the methods to recover I /Q signals, six-port receivers can be categorized into two different structures as shown in Fig. 1 [3]. ...
In this paper, a novel calibration algorithm based on real-valued time-delay neural network (RVTDNN) is proposed for the multiport receiver to recover I/Q signals from the received modulated signals, especially from wideband signals. All the system impairments, including the nonideal six-port correlator, the nonlinearity of the diodes, and the memory effects under the excitation of the wideband signals, are taken into consideration. The RVTDNN, which has three layers, consists of four inputs and two outputs (in-phase and quadrature signals), and its parameters (biases and weights) are all real-valued and are determined by the backpropagation algorithm. Finally, the proposed calibration method is validated by a 2-18-GHz six-port receiver under 3G and 4G signals. The performance of the error vector magnitude between the transmitted signals and received signals is always less than 1.8%, which validates the correctness of the proposed model.
... The EVM, sometimes also called receive constellation error (RCE), is an indicator of the quality and performance of communication systems. It can offer insightful information on the various imperfections such as carrier leakage, nonlinearity , I/Q mismatch and phase noise [14]. The EVM can be defined as the difference between the expected complex voltage value of a demodulated symbol and the value of the actual received symbol. ...
Direct conversion quadrature demodulator analysis based on recently fabricated V-band six-port circuit operating over 60 GHz band is presented in this paper. In order to obtain realistic system simulation results, the computer model of the six-port demodulator is implemented using Advanced Design System (ADS) software and S-parameter measurements of the integrated six-port circuit on thin alumina substrate. The performance of the proposed model is characterized in terms of the Error Vector Magnitude (EVM) for various M-PSK/M-QAM modulated signals. Very good demodulation results have been obtained over a 5 GHz band, from 60 to 65 GHz. These results provide further evidence that the six-port quadrature demodulator is a successful approach for homodyne or heterodyne transceivers designed for high-speed short-range wireless communication systems, such as today's WiGig or future millimeter wave 5G.
... The six-port based receiver systems offer wide frequency bandwidth coverage ideal for software defined radio applications [9]. Adding cognitive and intelligent features to it with the help of cognitive engine (CE) will pave the way for usefulness of six-port receivers for cognitive radios (CR) applications. ...
Six-port technique is a very accurate and cost effective method to determine the amplitude and phase of any input signal with respect to a known signal using only power or voltage measurements. This property of six-port technique has been variously exploited in a number of RF (radio frequency) and microwave applications. The present paper provides a very brief but wide review of the six-port technique for communication receiver applications. After providing a basic theory of six-port technique for single-band receiver application, the paper shows the usefulness of the technique for multi-band, MIMO (multiple-input and multiple-output) and CR (cognitive radio) receiver applications.
In this paper, a self-contained dual-input receiver architecture based on the interferometric technique is proposed and demonstrated for the first time for paralleled-multichannel wireless systems. Different from conventional counterparts, the proposed receiver consists of dual-input RF channel paths, and only one sole hardware is used to realize frequency translation, i.e., the conversion to intermediate frequency (IF) band. Demodulated IF signals can be extracted from two output ports instead of four ports in legacy multiport systems, thereby further reducing circuit complexity, size, cost, and power consumption. A mathematical model of the receiver architecture is formulated and applied to examine its modes of operation. For the proof of concept, a dual-band and dual-polarized prototype RX frontend is designed and fabricated to validate the proposed architecture. The transmission and demodulation of multiple digital modulation signals including QPSK, 16-QAM, 32-QAM, and 64-QAM are successfully demonstrated experimentally. Those measured results confirm that the proposed receiver architecture achieves good and desired performances. Based on the proposed self-contained dual-input receiver architecture, a multiband and multifunction polarization-diversified wireless system featuring compact size, low-cost, and low-power consumption suitable for 5G, 6G, and beyond can be realized.
A cooperative radar-communication (RadCom) system architecture employing a multi-port interferometer receiver is introduced and demonstrated for low-power and low-cost multifunction wireless applications. The proposed system operates in both radar sensing and radio communication modes, which are arranged in different time slots within a single hardware platform. In the radar sensing cycle, a triangular frequency modulated continuous-wave (FMCW) scheme is adopted for distance and velocity measurements. The radio cycle following the radar sensing cycle is used to communicate beat frequency information among different measurement stations for a cooperative radar operation, which can also be used for other data transmissions. The interferometric receiver for a unified multifunction operation benefits from the cooperative approach as it does not require a receiver front-end with a high dynamic range. The receiver architecture also makes use of a balanced detection scheme to suppress the frequency mixing components generated between radar echoes and cooperative radar responses, which eliminates undesired interferences and false targets as well as to enhance the signal quality. A mathematical model of the proposed sensing system is derived to design and implement the system for operation in a multi-station environment. The system performance consisting of two stations in a low microwave frequency band has been established and evaluated for both modes with several experiments. In radar sensing mode, the distance and velocity measurements demonstrate the target finding capability of our proposed system. In radio mode, the demodulation of various digitally modulated signals has been successfully studied at different data rates.
The realization and analysis of an implemented V-band six-port demodulator, operating over 60 GHz band, are presented in this paper. The performance of the design in real-time high-data-rate wireless data transmission is strongly proved using different modulated signals. The valid high data-rate demodulation results achieved over a 7 GHz band (from 57 to 64 GHz), provide a confirmation that this six-port interferometer receiver is an attractive proposition for homodyne or heterodyne transceivers designed for high-speed short-range wireless communication systems, such as future wireless small cell backhaul for 5G. The performance of the proposed direct conversion receiver is characterized in terms of the bit error rate (BER) and error vector magnitude (EVM) for various M-PSK/M-QAM demodulated signals. To verify the resulting data, the relation between the error vector magnitude and the bit error rate is also analyzed. Theoretical results are matched to measured values and validate that the EVM and BER are appropriate metrics for mm-wave channels limited by additive white Gaussian noise. In the last section, the proposed six-port interferometer is introduced for precise estimation of carrier frequency offset (CFO) and Doppler shift in V-band wireless systems. The final results, which include various modulation configurations at mega or Giga symbol rates generated by the implemented transmitter, are supported by laboratory measurements.
Radio frequency (RF), microwave, and millimeter-wave (mmW) multiport interferometric receivers present a competitive solution for the front-end reception of low-power multistandard and multifunction wireless applications. The systematic generation of rectified waves in a conventional direct-conversion interferometric receiver is highly related to temporal and power changes and the number of subsignals in the frequency band of interest. It can cause the receiver to saturate and, thus, requires auxiliary power-hungry tunable amplifiers and a data converter for compensation. This work presents a heterodyne detection in an RF/microwave interferometric receiver, the first of its kind, which separates the desired frequency signals from the rectified wave components with two output ports through a frequency offset. This architecture also makes use of the field-effect transistor (FET)-based power detectors to combine the received and reference signals, which reduces a theoretical multiport junction loss of 6 dB to 3 dB. In this way, the proposed receiver is set to support the development of an ultralow-power concurrent dual-band wireless system using a single wave-correlator circuit. A mathematical model of the proposed system is derived and subsequently prototyped using off-the-shelf components to evaluate its carrier-to-noise power ratio (CNR) and error vector magnitude (EVM) performances, which can be extended for integrated circuits (ICs) implementation, such as CMOS and III-V ICs. The power detectors only require a bias voltage at gate terminals with zero direct current (dc) power consumption for optimum voltage responsivity and CNR performances. The demodulation of various modulated digital signals, including QPSK, QAM-16, QAM-32, and QAM-64, has been successfully demonstrated in the 24- and 28-GHz mmW frequency bands at 4 MSps of the symbol rate with a maximum EVM of 11.43% root-mean-square (rms) free from any postprocessing linearization and calibration.
Die sechstorbasierte Empfängerarchitektur ist bereits seit den siebziger Jahren bekannt und erlangte in den vergangenen Jahren weltweit wieder vermehrt die Aufmerksamkeit verschiedener Forschungsgruppen. Dies liegt zum einen darin begründet, dass die Implementierung der Technologie in dem für neue Anwendungen oft verwendeten Frequenzbereich oberhalb von 10 GHz einfach möglich ist, und zum anderen daran, dass das hohe Phasenauflösungsvermögen dieser Architektur bereits vielfach gezeigt werden konnte. Durch diese Eigenschaften eignet sich die Sechstortechnik besonders für das sich in Entwicklung befindliche Feld der mikrowellenbasierten industriellen Sensorik. Hierfür werden günstige Sensoren mit kleinen Bauformen benötigt, an die hohe Anforderungen bezüglich Genauigkeit und Latenz gestellt werden. Inwieweit das Sechstor dazu geeignet ist, ist Untersuchungsgegenstand dieser Abhandlung. Nach einer Einführung in die Funktionsweise der Architektur folgt zu diesem Zweck ein Vergleich, der die Vorteile des additiven Mischansatzes der Sechstortechnologie gegenüber einem ebenfalls passiven, jedoch multiplikativen Mischer zeigt. Anschließend werden für die industrielle Sensorik wichtige Messaufgaben, wie die Frequenzmessung, die hochgenaue Abstandsmessung sowie die Vibrationsanalyse und deren jeweilige Implementierungen mit der Sechstorarchitektur, eingeführt. Außerdem werden verschiedene Fehlereinflüsse untersucht und angepasste Linearisierung- und Kompensationsstrategien vorgestellt. Um die Realisierbarkeit der dargestellten Anwendungen zu beweisen, werden ausgewählte Demonstratoren und deren Ergebnisse dargestellt. Diese zeigen für die Abstandsmessung Genauigkeiten von wenigen Mikrometern und für die Frequenzmessung einen relativen Fehler weniger ppm. Darüber hinaus wird auch ein erster Prototyp und dessen optimierter Entwicklungsprozess für einen industriellen Abstandssensor vorgestellt, der auf der Sechstortechnik beruht und eine erste kommerzielle Realisierung dieser Technik für die Abstandsmessung darstellt.
