A wideband 2 × 13-bit all-digital I/Q RFDAC

Alavi, Morteza S.

doi:10.1016/b978-0-12-802263-4.00010-6

Cited by 20 publications

(35 citation statements)

References 29 publications

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“…This gain comes at the cost of doubling the sampling rate f s of the DAC which, from (9), doubles the power consumed. As pointed out in [33], high over sampling is not practical for wide band systems due to the linear increase in power consumption.…”

Section: Sdma Transmissionmentioning

confidence: 99%

A Case for Digital Beamforming at mmWave

Dutta

Barati

Ramírez

et al. 2020

IEEE Trans. Wireless Commun.

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Due to the heavy reliance of millimeter-wave (mmWave) wireless systems on directional links, beamforming (BF) with high-dimensional arrays is essential for cellular systems in these frequencies.How to perform the array processing in a power efficient manner is a fundamental challenge. Analog and hybrid BF require fewer analog-to-digital and digital-to-analog converters (ADCs and DACs), but can only communicate in a small number of directions at a time, limiting directional search, spatial multiplexing and control signaling. Digital BF enables flexible spatial processing, but must be operated at a low quantization resolution to stay within reasonable power levels. This decrease in quantizer resolution introduces noise in the received signal and degrades the quality of the transmitted signal.To assess the effect of low-resolution quantization on cellular system, we present a simple additive white Gaussian noise (AWGN) model for quantization noise. Simulations with this model reveal that at moderate resolutions (3-4 bits per ADC), there is negligible loss in downlink cellular capacity from quantization. In essence, the low-resolution ADCs limit the high SNR, where cellular systems typically do not operate. For the transmitter, it is shown that DACs with 4 or more bits of resolution do not violate the adjacent carrier leakage limit set by 3 rd Generation Partnership Project (3GPP) New Radio (NR) standards for cellular operations. Further, this work studies the effect of low resolution quantization on the error vector magnitude (EVM) of the transmitted signal.In fact, our findings suggests that low-resolution fully digital BF architectures can be a power efficient alternative to analog or hybrid beamforming for both transmitters and receivers at millimeter wave. 2 Millimeter wave, 5G cellular, Low resolution quantizers, Digital beamforming.

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Section: Sdma Transmissionmentioning

confidence: 99%

A Case for Digital Beamforming at mmWave

Dutta

Barati

Ramírez

et al. 2020

IEEE Trans. Wireless Commun.

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“…The first digital-intensive transmitter architectures targeted for wideband operation were based on the RF-DAC concept [1], [2]. Several Cartesian [3]- [8] and polar [9]- [12] transmitters based on high amplitude resolution RF-DACs have since been reported, but they are susceptible to time-domain non-idealities and code-dependent output impedance variation [13]- [17].…”

Section: Introductionmentioning

confidence: 99%

Digital Interpolating Phase Modulator for Wideband Outphasing Transmitters

Lemberg

Kosunen

Roverato

et al. 2016

IEEE Trans. Circuits Syst. I

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Radio transmitters are evolving towards digitalintensive solutions to exploit reconfigurability and benefit from CMOS process scaling. Outphasing has been identified as a suitable candidate for digital wideband transmitters. However, with recent digital-intensive outphasing transmitters the achieved performance in terms of adjacent channel leakage ratio (ACLR) has been limited. This paper identifies the sampling images of the modulating phase signal as the main factor limiting the ACLR of digital outphasing transmitters. We present a new digital interpolating phase modulator architecture, capable of providing significantly better sampling image attenuation. When evaluated in outphasing configuration with a 100 MHz OFDM signal at the carrier frequency of 2.46 GHz, and 10-bit phase resolution, the proposed solution achieves an ACLR of-59 dBc, compared to-43 dBc achievable with the phase modulator architecture utilized in state-of-the-art digital outphasing transmitters. The proposed digital interpolating phase modulator is also capable of custom carrier generation, a straightforward method for generating an arbitrary carrier frequency up to 1.25 times the phase modulator sampling rate.

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“…Therefore, due to the sampling nature of the multiplexer, some aliases phenomena will appear in the spectrum and the baseband signal will be upconverted at f IF and at all of its odd harmonics, i.e. 3f IF , 5f IF , 7f IF ... [7]. The energies of replicas will be shaped by the first-order sinc transfer function of the multiplexer due to its sample-and-hold behavior.…”

Section: Rf-dacmentioning

confidence: 99%

A digital up-sampling technique for a heterodyne digital centric transmitter

Bousseaud

Negra

2015

2015 German Microwave Conference

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In this paper, a digital up-sampling technique is presented for digital communication transmitters. This method allows to up-sample the I/Q baseband modulated signals to an intermediate frequency based on a 4:1 multiplexing technique, before being again up-converted at the carrier frequency. The frequency conversion is made in two steps and permits to avoid the nonlinear behavior of direct up-converting architectures. Also, the mutual coupling between the output power amplifier (PA) and the phase-locked loop (PLL) can be reduced by choosing the local oscillator frequency (LO) far enough from the carrier output frequency. A fully integrated CMOS transmitter with an on chip PA is thus becoming feasible. A PLL at the frequency of 4.8 GHz has been designed in a 65 nm CMOS process along with a digital 4:1 multiplexer in order to target the band-VII Long Term Evolution (LTE) applications in the 2.55 GHz frequency.

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A wideband 2 × 13-bit all-digital I/Q RFDAC

Cited by 20 publications

References 29 publications

A Case for Digital Beamforming at mmWave

A Case for Digital Beamforming at mmWave

Digital Interpolating Phase Modulator for Wideband Outphasing Transmitters

A digital up-sampling technique for a heterodyne digital centric transmitter

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