An overview of fast DC-DC converters for envelope amplifier in RF transmitters

Abstract-The use of techniques such as envelope tracking (ET) and envelope elimination and restoration (EER) can improve the efficiency of radio frequency power amplifiers (RFPA). In both cases, high-bandwidth DC/DC converters called envelope amplifiers (EA) are used to modulate the supply voltage of the RFPA. This paper addresses the analysis and design of a modified two-phase Buck converter optimized to operate as EA. The effects of multiphase operation on the tracking capabilities are analyzed. The use of a fourth-order output filter is proposed to increase the attenuation of the harmonics generated by the PWM operation, thus allowing a reduction of the ratio between the switching frequency and the converter bandwidth. The design of the output filter is addressed considering envelope tracking accuracy and distortion caused by the side bands arising from the nonlinear modulation process. Finally, the proposed analysis and design methods are supported by simulation results, as well as demonstrated by experiments obtained using two 100-W, 10-MHz, two-phase Buck EAs capable of accurately tracking a 1.5-MHz bandwidth OFDM signal.

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“…11(b) when the converter angular switching frequency ω s is 4 rad/s. As (19) shows, the value of ω env max is 1 rad/s. This means that nf s = 4.…”

Section: A Design Proceduresmentioning

confidence: 96%

“…Therefore, this attenuation can be expressed as a function of nf s , e h max , and δ LSB , as shown in Fig. 14 As an example, let us evaluate the value of δ LSB corresponding to v DA reproducing the envelope signal x(t) given in (19) and shown in Fig. 11(b) when the converter angular switching frequency ω s is 4 rad/s.…”

Section: A Design Proceduresmentioning

confidence: 99%

Design of a Two-Phase Buck Converter With Fourth-Order Output Filter for Envelope Amplifiers of Limited Bandwidth

Sebastián

Miaja

Ortega-González

et al. 2014

IEEE Trans. Power Electron.

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“…Several architectures have been proposed in the literature for envelope modulators, which have different pros and cons. Low-drop-out regulators [4], switch-mode PAs [5][6][7], series-parallel combined linear and switching PAs [8][9][10][11] are the structures that are used in previous work. Low-drop-out regulators have wide bandwidth and low output ripples.…”

Section: Introductionmentioning

confidence: 99%

An adaptive digital processor for power efficiency enhancement in hybrid supply modulators

Salimi

Dehghani

Nabavi

2015

Circuit Theory & Apps

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SUMMARYA novel digital envelope modulator for envelope tracking radio frequency power amplifier is presented in this paper. The proposed modulator consists of a parallel combination of linear class AB and switching class D power amplifiers that are controlled digitally. In the previous analog architectures, the requirements needed for the AB operational amplifier such as high-current driving capability, high bandwidth and large output swing is usually obtainable at high overall static power dissipation. The digitally controlled power opamp presented here not only provides the aforementioned requirements but also reduces power dissipation compared with previous work. Furthermore, the digital control of the modulator makes it adaptive to the input signal variations in comparison with conventional analog parallel hybrid envelope modulators. The digital processor of the modulator is evaluated with a 45-nm complementary metal oxide semiconductor technology. The overall power consumption of the digital processor is around 142 mW at 1.5-GHz clock frequency. As an application, the designed digital class AB is incorporated in a complete envelope modulator architecture. The overall efficiency of the modulator, including the digital processor power consumption, is around 82% at an average 32 dBm output power for a 5-MHz input signal.

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“…As Power converters are quite more flexible in terms of control, have become the most concerning technology for researchers in modern power system. DC-DC power converters are widely used in variety of applications in terms of their high efficiency and low output ripple, such as portable devices, energy-harvesting applications and Radio Frequency (RF) power amplifiers that are in need of highly efficient and stable power supply [1,2,3].…”

Section: Introductionmentioning

confidence: 99%

Approach to the Modeling of LDO-Assisted DC-DC Voltage Linear Regulators

Sedaghati¹,

García²,

Vilella³

2017

REPQJ

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Abstract. This paper presents the design of a LDO-assisted DC-DC converters in Cadence Virtuoso based on a 350-nm CMOS technology. This kind of voltage regulators consists of a switching converter together with a classic or LDO (low dropout) linear voltage regulator. While the linear regulator provides the constant output voltage, the switching converter conducts nearly all the current provided in the output load, and keeping the regulator current close to zero where the higher efficiency is achieved. In addition, current article shows the modeling in Matlab/Simulink. This modeling is mandatory in order to predict and assure the stability of the circuit. In addition, it can allow improving the performance of the circuit.

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An overview of fast DC-DC converters for envelope amplifier in RF transmitters

Cited by 16 publications

References 28 publications

Design of a Two-Phase Buck Converter With Fourth-Order Output Filter for Envelope Amplifiers of Limited Bandwidth

Design of a Two-Phase Buck Converter With Fourth-Order Output Filter for Envelope Amplifiers of Limited Bandwidth

An adaptive digital processor for power efficiency enhancement in hybrid supply modulators

Approach to the Modeling of LDO-Assisted DC-DC Voltage Linear Regulators

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