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. 2018 Feb 20;18(2):626.
doi: 10.3390/s18020626.

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

Anis Ben Arfi  1 , Fahmi Elsayed  2 , Pouya M Aflaki  3 , Brad Morris  4 , Fadhel M Ghannouchi  5
Affiliations

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

Anis Ben Arfi et al. Sensors (Basel). .

Abstract

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.

Keywords: dual branch amplification; highly-efficient transmitter; multi-level Complex Delta-Sigma Modulator; switch mode power amplifier.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Delta Sigma modulator blocks; (b) CxDSM block diagram.
Figure 2
Figure 2
The three-level de-multiplexing quantization process.
Figure 3
Figure 3
Dual-branch DSM architecture.
Figure 4
Figure 4
Time-domain decomposition of the three level-signals.
Figure 5
Figure 5
Standalone SMPAs and connected SMPAs and their drain efficiency equations.
Figure 6
Figure 6
Dual-branch DSM setup.
Figure 7
Figure 7
Normalized input and output three-level CxDSM signal.
Figure 8
Figure 8
Normalized input and output three-level DSM signal after QNRIF.
Figure 9
Figure 9
The amplification block stage setup.
See this image and copyright information in PMC

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