Aliasing-Free Digital Pulse-Width Modulation for Burst-Mode RF Transmitters

Hausmair, Katharina; Chi, Shuli; Singerl, Peter; Vogel, Christian

doi:10.1109/tcsi.2012.2215776

Cited by 66 publications

(73 citation statements)

References 30 publications

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“…Therefore, a nonconstant-envelope communication standard signal needs to be converted into a suitable PA driving signal. To obtain the driving signal for the PA, Σ∆-modulators or pulse-width modulators can be used [4], [5]. These modulators inherently create a large amount of out-of-band power that needs to be removed by a bandpass filter (BPF) after power amplification to obtain a standard conform transmission signal.…”

Section: Introductionmentioning

confidence: 99%

How to reach 100% coding efficiency in multilevel burst-mode RF transmitters

Hausmair

Chi

Vogel

2013

2013 IEEE International Symposium on Circuits and Systems (ISCAS2013)

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Among other goals, multilevel burst-mode radio frequency (RF) transmitters have to achieve two main objectives: high efficiency, and good transmission signal quality. Both of these goals depend, to a large extent, on the driving signal modulator, which can, for example, be a digital pulse-width modulator. However, conventional digital pulse-width modulation (PWM) contains aliasing distortion that prevents achieving satisfying transmission signal quality.In this paper, an aliasing-free digital multilevel PWM method is introduced that allows for achieving good transmission signal quality, while at the same time offering the potential of reaching a coding efficiency of 100%. The mathematical equations for aliasing-free digital PWM are extended in a way that makes them suitable for the use in multilevel burst-mode RF transmitters. It is then shown how the aliasing-free multilevel PWM method can be used to achieve 100% coding efficiency. Simulations demonstrate the performance capabilities of the proposed PWM method.

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Section: Introductionmentioning

confidence: 99%

How to reach 100% coding efficiency in multilevel burst-mode RF transmitters

Hausmair

Chi

Vogel

2013

2013 IEEE International Symposium on Circuits and Systems (ISCAS2013)

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“…The amplitude aliasing distortion [65,71] is due to the digital implementation of the pulse-width modulator. The digital PWM signal is a sampled version of the analog PWM signal, hence the rising and falling edges occur only at integer multiples of the sampling period.…”

Section: Amplitude Aliasing Distortionmentioning

confidence: 99%

“…The digital PWM signal is a sampled version of the analog PWM signal, hence the rising and falling edges occur only at integer multiples of the sampling period. The digital PWM signal and its spectrum [71,72] are given as where n is the sampling index and T s is the sampling period. The plot of the digital PWM and its spectrum is shown in Fig.…”

Section: Amplitude Aliasing Distortionmentioning

confidence: 99%

“…The aliasing-Free PWM transmitter [71,[73][74][75] (AF-PWMT) eliminates the aliasing and image distortion by limiting the number of harmonics of the digital PWM signal. The block diagram of the AF-PWMT is shown in Fig.…”

Section: Aliasing-free Pwm Transmitter 421 Conceptmentioning

confidence: 99%

“…The transmitter separates the baseband signal x(t) into its amplitude a(t) and phase φ(t) components. The amplitude component generates a digital PWM signal with finite harmonic components, hereafter referred to as a band-limited PWM (BL-PWM) signal [71], which is given as where τ (nT S ) = a(nT S )T , a(nT S ) is the baseband signal amplitude at instance nT S and K is the total number of harmonics in the BL-PWM signal. In order to eliminate the aliasing and image distortions, K must ensure the following conditions…”

Section: Aliasing-free Pwm Transmitter 421 Conceptmentioning

confidence: 99%

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Pulse-Width Modulated RF Transmitters

Haque¹

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To my mother, father, and uncle (mamoo), AbstractThe market for wireless portable devices has grown significantly over the recent years. Wireless devices with ever-increased functionality require high rate data transmission and reduced costs. High data rate is achieved through communication standards such as LTE and WLAN, which generate signals with high peak-to-average-power ratio (PAPR), hence requiring a power amplifier (PA) that can handle a large dynamic range signal. To keep the costs low, modern CMOS processes allow the integration of the digital, analog and radio functions on to a single chip. However, the design of PAs with large dynamic range and high efficiency is challenging due to the low voltage headroom.To prolong the battery life, the PAs have to be power-efficient as they consume a sizable percentage of the total power. For LTE and WLAN, traditional transmitters operate the PA at back-off power, below their peak efficiency, whereas pulse-width modulation (PWM) transmitters use the PA at their peak power, resulting in a higher efficiency. PWM transmitters can use both linear and SMPAs where the latter are more power efficient and easy to implement in nanometer CMOS. The PWM transmitters have a higher efficiency but suffer from image and aliasing distortion, resulting in a lower dynamic range, amplitude and phase resolution.This thesis studies several new transmitter architectures to improve the dynamic range, amplitude and phase resolution of PWM transmitters with relaxed filtering requirements. The architectures are suited for fully integrated CMOS solutions, in particular for portable applications.The first transmitter (MAF-PWMT) eliminates aliasing and image distortions while allowing the use of SMPAs by combining RF-PWM and band-limited PWM. The transmitter can be implemented using all-digital techniques and exhibits an improved linearity and spectral performance. The approach is validated using a Class-D PA based transmitter where an improvement of 10.2 dB in the dynamic range compared to a PWM transmitter for a 1.4 MHz of LTE signal is achieved.The second transmitter (AC-PWMT) compensates for aliasing distortion by combining PWM and outphasing. It can be used with switch-mode PAs (SMPAs) or linear PAs at peak power. The proposed transmitter shows better linearity, improved spectral performance and increased dynamic range as it does not suffer from AM-AM distortion of the PAs and aliasing distortion due to digital PWM. The idea is validated using push-pull PAs and the proposed transmitter shows an improvement of 9 dB in the dynamic range as compared v vi Abstract to a PWM transmitter using digital pulse-width modulation for a 1.4 MHz LTE signal.The third transmitter (MD-PWMT) is an all-digital implementation of the second transmitter. The PWM is implemented using a Field Programmable Gate Array (FPGA) core, and outphasing is implemented as pulse-position modulation using FPGA transceivers, which drive two class-D PAs. The digital implementation offers the flexibility to adapt the transmitter...

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Power‐efficient burst‐mode RF transmitter based on reference‐adaptive multilevel pulse‐width modulation

Arian

Jannesari

2017

Circuit Theory & Apps

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Summary Burst‐mode operation of power amplifier (PA) based on multilevel pulse‐width modulation (MPWM) has been frequently discussed as a potential solution to achieve higher efficiency in radio frequency (RF) transmitters. In this paper, a novel multilevel PWM modulator is proposed that utilizes adaptive triangular reference waveforms. As compared with conventional MPWM modulators, the proposed architecture provides significant wider design space such that the efficiency of system can be effectively optimized. A general transmitter architecture based on the proposed concept is analyzed in terms of power efficiency. Efficiency optimization procedures are presented according to input magnitude statistics. Based on the proposed modulator, an optimized 2.4‐GHz RF transmitter is designed in a 0.18‐μm complementary metal‐oxide‐semiconductor (CMOS) process. The circuit‐level simulations show that it delivers 25.8‐dBm peak output power with 46.1% peak efficiency. For a 20‐MHz worldwide interoperability for microwave access (WiMAX) signal with 8.5‐dB peak‐to‐average‐power ratio (PAPR), this transmitter achieves 28.8% (average) efficiency at 17.3‐dBm (average) output power with an error vector magnitude (EVM) of 2.97% rms.

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Aliasing-Free Digital Pulse-Width Modulation for Burst-Mode RF Transmitters

Cited by 66 publications

References 30 publications

How to reach 100% coding efficiency in multilevel burst-mode RF transmitters

How to reach 100% coding efficiency in multilevel burst-mode RF transmitters

Pulse-Width Modulated RF Transmitters

Power‐efficient burst‐mode RF transmitter based on reference‐adaptive multilevel pulse‐width modulation

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