Inter-band carrier aggregation digital transmitter architecture with concurrent multi-band delta-sigma modulation using out-of-band noise cancellation

Chung, Suk Bum; Ma, Rui; Shinjo, Shintaro; Teo, Koon Hoo

doi:10.1109/mwsym.2015.7166934

Cited by 16 publications

(5 citation statements)

References 7 publications

(8 reference statements)

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“…The 1-bit quantizer has an output bit-stream of 0 s (zeros) and 1 s (ones), hence the conversion of a continuous signal into a bi-level modulated signal. This output bi-level signal is suitable for driving a Switching Mode Power Amplifier (SMPA) [ 6 ]. The quantizer should operate at a high oversampling frequency.…”

Section: Complex Multi-bit Delta-sigma Modulatormentioning

confidence: 99%

“…Previous works have focused on improving the performance of DSM-based transmitters in terms of Coding Efficiency (CE) and improvement of the DSM quantization noise shaping, mainly by increasing the order of the DSM or increasing the number of quantization levels. In [ 3 , 4 ], multi-level DSM was investigated, dual-band DSM transmitters were demonstrated in [ 5 , 6 ] focused on the application of carrier aggregation on DSM signals.…”

Section: Introductionmentioning

confidence: 99%

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Three-Level De-Multiplexed Dual-Branch Complex Delta-Sigma Transmitter

Arfi

Elsayed

Aflaki

et al. 2018

Sensors

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In this paper, a dual-branch topology driven by a Delta-Sigma Modulator (DSM) with a complex quantizer, also known as the Complex Delta Sigma Modulator (CxDSM), with a 3-level quantized output signal is proposed. By de-multiplexing the 3-level Delta-Sigma-quantized signal into two bi-level streams, an efficiency enhancement over the operational frequency range is achieved. The de-multiplexed signals drive a dual-branch amplification block composed of two switch-mode back-to-back power amplifiers working at peak power. A signal processing technique known as quantization noise reduction with In-band Filtering (QNRIF) is applied to each of the de-multiplexed streams to boost the overall performances; particularly the Adjacent Channel Leakage Ratio (ACLR). After amplification, the two branches are combined using a non-isolated combiner, preserving the efficiency of the transmitter. A comprehensive study on the operation of this topology and signal characteristics used to drive the dual-branch Switch-Mode Power Amplifiers (SMPAs) was established. Moreover, this work proposes a highly efficient design of the amplification block based on a back-to-back power topology performing a dynamic load modulation exploiting the non-overlapping properties of the de-multiplexed Complex DSM signal. For experimental validation, the proposed de-multiplexed 3-level Delta-Sigma topology was implemented on the BEEcube™ platform followed by the back-to-back Class-E switch-mode power amplification block. The full transceiver is assessed using a 4th-Generation mobile communications standard LTE (Long Term Evolution) standard 1.4 MHz signal with a peak to average power ratio (PAPR) of 8 dB. The dual-branch topology exhibited a good linearity and a coding efficiency of the transmitter chain higher than 72% across the band of frequency from 1.8 GHz to 2.7 GHz.

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Section: Complex Multi-bit Delta-sigma Modulatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three-Level De-Multiplexed Dual-Branch Complex Delta-Sigma Transmitter

Arfi

Elsayed

Aflaki

et al. 2018

Sensors

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“…In addition, quadrature modulation is performed by utilizing the digital signal processing in FPGA, and the intermediate frequency or RF frequency is directly output at the DAC whose output frequency is below 3 GHz (first Nyquist zone). The 1-bit BP-DSM has also been demonstrated to output single-band and concurrent multi-band at RF frequencies including 3.5 GHz [23].…”

Section: Introductionmentioning

confidence: 99%

Wideband 1-Bit Bandpass Delta Sigma Modulator Using Elliptic Filter in Noise Transfer Function

Maehata

Suematsu

2022

IEEE Access

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A 1-bit band-pass delta-sigma modulator (BP-DSM), which utilizes oversampling technology, allows a modulated signal to be directly output by using a high-speed 1-bit digital pulse train, thus realizing miniaturization of transmitters. For 1-bit BP-DSM, the noise transfer function (NTF) is used to suppress quantization noise power in the transmission band and a guideline of out-of-band gain of |NTF|< 1.5 is used to prevent oscillation. However, in previous studies, such as Butterworth and inverse Chebyshev filters, the out-of-band gain was designed indirectly by tuning the zeros and poles in the transmission band and thus, was not stabilized sufficiently. Furthermore, even though the zeros of the NTF are identical to the poles of the loop filter, there are still widely used designs in which the zeros are set on the unit circle, making stabilization quite difficult. Therefore, in this paper, we propose a feasible implementation of the NTF for 1-bit BP-DSM with an elliptic filter that can be used to set not only in-band but also out-of-band gain, in which both the zeros and poles are set inside the unit circle. As a design result, a modulation bandwidth of 400 MHz as a relative bandwidth of 11%, a noise suppression bandwidth of 800 MHz, and an adjacent channel leakage power ratio of 50 dB were achieved at a center frequency of 3.6 GHz, enabling a wider bandwidth and higher SNR than before by improving the stability.INDEX TERMS Delta-sigma modulator, quantization, 5G mobile communication, software defined radio, wideband.

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“…1. References [49]- [52], [60]- [63] are not included since they are not implemented by CMOS or FPGA, but by offline processing. on option 8 and other LLS candidates require a complete RF layer implemented in the analog domain at each remote cell site, which increases the complexity and cost of small cells.…”

mentioning

confidence: 99%

“…As a cornerstone of SDR, all-digital RF transceiver based on delta-sigma modulation has attracted intensive research interest due to its low cost and flexibility to accommodate multiband multi-RAT operations. Both transmitter [30]- [52] and receiver [53]- [59] designs have been reported, and various delta-sigma modulators, including lowpass [30], [32]- [34], [36]- [39], [41]- [45], [47], [48], bandpass [31], [35], and multiband [40], [49]- [52] have been demonstrated. To relax the FPGA speed requirement, several time-interleaving or parallel processing techniques are also presented [38], [39], [43]- [45], [47], [48].…”

mentioning

confidence: 99%

Delta-Sigma Modulation for Next Generation Fronthaul Interface

Wang

Jia

Campos

et al. 2019

J. Lightwave Technol.

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A new function split option for the next generation fronthaul interface (NGFI) is demonstrated based on all-digital RF transmitter using bandpass delta-sigma modulation. Different from other low layer split (LLS) options, such as option 6 (MAC-PHY), 7 (high-low PHY), and 8 (CPRI), the proposed option 9 implements RF functions in the digital domain, and splits within the RF layer, with high-RF layer centralized in the distributed unit (DU) and low-RF layer distributed in remote radio units (RRUs). A proof-of-concept all-digital RF transmitter based on real-time delta-sigma modulation is implemented using a Xilinx Virtex-7 FPGA. A 5-GSa/s delta-sigma modulator is demonstrated to encode LTE/5G signals with bandwidth up to 252 MHz and modulation format up to 1024-QAM to a 5-Gb/s OOK signal, which is transmitted over 30-km single-mode fiber from DU to RRU. To relax the FPGA speed requirement, a 32-pipeline architecture is designed. Two-carrier aggregation of 5G and 14-carrier aggregation of LTE signals are demonstrated with error vector magnitude (EVM) performance satisfying the 3GPP specifications. Compared with option 8 (CPRI), although the proposed option 9 split occurs at a lower level, it offers improved spectral efficiency and reduced NGFI data rate than CPRI. Moreover, other LLS options, such as 6, 7, and 8, all require a complete RF layer implemented in the analog domain at remote cell sites; whereas option 9 realizes high-RF layer in the digital domain at DU, and eliminates the need of analog RF devices, such as DAC, local oscillator and mixer at RRU, which not only makes low-cost, energy-efficient, and small-footprint cell sites possible for the wide deployment of small cells, but also paves the road toward software defined radio (SDR) and virtualization of DU and RRU for improved compatibility and reconfigurability among multiple radio access technologies (multi-RATs). Given its centralized architecture and deterministic latency, option 9 is suitable for radio coordination applications, and has potential in low-frequency narrowband scenarios with cost, power, and/or size sensitive cell sites, such as massive machine type communication (mMTC) and narrowband internet of things (NB-IoT). Index Terms-All-digital RF transmitter, delta-sigma modulation, fronthaul, NGFI, software defined radio. I. INTRODUCTION T HE emerging video-intensive and bandwidth-consuming services, e.g., virtual reality, augmented reality, immersive applications, are driving the explosive growth of mobile data traffic [1]-[3], making radio access networks (RAN) become

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Inter-band carrier aggregation digital transmitter architecture with concurrent multi-band delta-sigma modulation using out-of-band noise cancellation

Cited by 16 publications

References 7 publications

Three-Level De-Multiplexed Dual-Branch Complex Delta-Sigma Transmitter

Three-Level De-Multiplexed Dual-Branch Complex Delta-Sigma Transmitter

Wideband 1-Bit Bandpass Delta Sigma Modulator Using Elliptic Filter in Noise Transfer Function

Delta-Sigma Modulation for Next Generation Fronthaul Interface

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