1549-7747 (c) 2017 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TCSII.2017.2777993, IEEE Transactions on Circuits and Systems II: Express Briefs IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—II: EXPRESS BRIEFS 1 Abstract—A concurrent dual-band receiver based on a single multiport correlator is proposed in this paper to down-convert dual-band radio frequency (RF) signals. The system configuration, output power as well as its spectrum analysis are discussed, and then a generalized baseband signal recovery theory is put forward. Next, the calibration algorithm based on real-valued time-delay neural network (RVTDNN), which can take the system impairments and signal distortions into consideration, is proposed to retrieve two baseband signals, simultaneously. Finally, the six-port receiver is tested under the common modulated signals, and the measured error vector magnitudes (EVMs) between the transmitted and the received signals are all less than 2%. Index Terms—Concurrent, dual band, receiver, multiport correlator, calibration algorithm. I. INTRODUCTION ONCURRENT dual-band or multi-band radio frequency (RF) devices and front-ends have become necessary and important in modern wireless communication systems because they can operate at two or more frequencies concurrently and the system cost will be decreased, correspondingly. Therefore, different kinds of multi-band or multi-mode receivers have been proposed in [1]-[4]. It can be seen that the receivers [1]-[3] are all based on more than one active nonlinear mixers, which lead to high cost and high power consumption. In addition, two parallel receiving paths are adopted in [1], [3] to realize the Manuscript received Aug. 14, 2017, revised Oct. 22, 2017, accepted Nov. 23, 2017. This work was fully supported by National Natural Science Foundation of China (No. 61422103, and No. 61671084), National Key Basic Research Program of China (973 Program) (No. 2014CB339900), BUPT Excellent Ph.D. Students Foundation (CX2017406), the Alberta Innovates Technology Future (AITF), the National Science and Engineering Research Council (NSERC) of Canada, and the Canada Research Chairs (CRC) programs. Weiwei Zhang is with the Beijing Key Laboratory of Work Safety Intelligent Monitoring, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China, and also with the Intelligent RF Radio Laboratory (iRadio Lab), Department of Electrical and Computer Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada. (e-mail: clarence.zhang11@gmail.com). Abul Hasan, Fadhel M. Ghannouchi, Mohamed Helaoui, and Xiang Li are with the Intelligent RF Radio Laboratory (iRadio Lab), Department of Electrical and Computer Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada. (e-mail: ahasan@ucalgary.ca, fghannou@ucalgary.ca) Yongle Wu, Linglong Meng, and Yuanan Liu are with the Beijing Key Laboratory of Work Safety Intelligent Monitoring, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China. (e-mail: wuyongle138@gmail.com, linglongm@126.com). dual-band or dual-mode applications, which increase the system complexity. Furthermore, there are many other issues related to multi-band/ multi-mode receivers [2]-[3]. For example, the realization of the image-reject filters and the switchable harmonic mixer [2] make the system very expensive in spite of high dynamic range achieved. Self-generated distortion due to nonlinearity and inter-band modulation caused by mixing of two different signals [3] deteriorate the receiver and lower the signal to noise ratio. Compared with the receivers proposed [1]-[3], a novel concurrent dual-band multi-port receiver is proposed in [4]. It is well known that the zero intermediate frequency (IF) receivers in [4]-[11], which are based on the passive multi-port correlator and the Schottky diode detectors, feature more advantages compared to the receivers in [1]-[3], such as broadband or multi-band performance, lower cost, lower power consumption, and compatibility with the digital signal processor, etc. However, the calibration model proposed in [4] is only used for the weekly nonlinear case because it fails to mitigate and compensate for the high order cross-band and inter-band distortion that falls within the receiver band. Therefore, this paper provides a new calibration technique based on the modified real-valued time-delay neural network (RVTDNN) [11] for the concurrent dual-band multi-port receiver. The problem formulation based on RVTDNN and the proposed calibration method used in this paper are different from those in [4]. Firstly, the output powers of the diode power detectors are calculated, and their spectra are obtained based on the Fourier transformation in this paper. Secondly, the baseband signal recovery theory is different from the one presented in [4], which has been discussed in Section II-B and III-C. Modified memory polynomial (MMP) model is used in [4], however, a more robust model based on RVTDNN is adopted in this paper. Hence, the cross-band and inter-band intermodulation have been taken into consideration to improve the performance of the receiver, which is validated in Section III-C. Notably, only single-band RF signal can be demodulated in [11], however, two different baseband signals can be retrieved simultaneously based on the different circuit structure, signal selection, analytical process, and calibration method. Based on the above analysis, the innovations and contributions of this paper are: 1) demodulation of two different baseband signals with high performance from the dual-band RF signal simultaneously using RVTDNN, 2) generalized Concurrent Dual-Band Receiver Based on the Multi-Port Correlator for Wireless Applications Weiwei Zhang, Graduate Student Member, IEEE, Abul Hasan, Graduate Student Member, IEEE, Fadhel M. Ghannouchi, Fellow, IEEE, Mohamed Helaoui, Member, IEEE, Xiang Li, Student Member, IEEE, Yongle Wu, Senior Member, IEEE, Linglong Meng, Yuanan Liu C