CMOS Linear Power Amplifier with Envelope Tracking Operation (Invited Paper)

Park, Byungjoon; Kim, Jooseung; Cho, Yunsung; Jin, Sangsu; Kang, Daehyun; Kim, Bumman

doi:10.5515/jkiees.2014.14.1.1

Cited by 20 publications

(6 citation statements)

References 20 publications

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“…A hysteretic control method is very popular for controlling the state of the switching converter [7]- [21]. With this method, the magnitude and polarity of the sensed sourcing and sinking currents in the linear regulator determine whether the switching converter is in ON state or OFF state.…”

Section: B Methods Of Switch Current Level Controlmentioning

confidence: 99%

Highly Efficient RF Transmitter Over Broad Average Power Range Using Multilevel Envelope-Tracking Power Amplifier

Kim

Cho

et al. 2015

IEEE Trans. Circuits Syst. I

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We present a highly efficient RF transmitter over broad average power range using a multilevel envelope-tracking power amplifier (ML-ET PA). The ML-ET PA delivers enhanced efficiency at a back-off power region for handset applications. The supply modulator consists of a linear regulator and a switching converter. The DC supply of the linear regulator is adjusted according to the average power of the envelope signal, and the power-supply-independent class-AB output stage is employed to avoid the crossover distortion generated by the different DC supply voltages. The switch current level is not optimally adjusted by itself following the power back-off level, because the DC supply voltages of the linear regulator and switching converter are different. For the optimum operation over the entire power region, the switch current level is adjusted by detecting the input envelope voltage level. For a 20-MHz long term evolution signal with a 7.5 dB peak-to-average power ratio, the proposed supply modulator delivers a peak voltage of 4.5 V to a 6.5 load with a measured efficiency of 75.9%. The proposed ET PA delivers a power-added efficiency (PAE) of 40%, gain of 28.8 dB, evolved universal terrestrial radio access adjacent channel leakage ratio of 35.3 dBc, and error vector magnitude of 3.23% at an average output power of 27 dBm and an operating frequency of 1.71-GHz. At a 10 dB back-off point, the PAE is improved from 14.5% to 18.7% compared to the conventional ET PA.Index Terms-Envelope tracking (ET), linear regulator, long term evolution (LTE), power amplifier (PA), supply modulator, switching converter.

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Section: B Methods Of Switch Current Level Controlmentioning

confidence: 99%

Highly Efficient RF Transmitter Over Broad Average Power Range Using Multilevel Envelope-Tracking Power Amplifier

Kim

Cho

et al. 2015

IEEE Trans. Circuits Syst. I

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“…To reduce such loss, an offchip transformer can be used. Off-chip transformers are designed on an integrated passive device (IPD) [18] or a printed circuit board (PCB) [29,30]. A transmission-line transformer (TLT) transmits the energy from the input to the output by a coupled transmission line mode and not by flux-leakage as in a conventional transformer.…”

Section: Output Matching Networkmentioning

confidence: 99%

“…The envelope shaping methods have been investigated for optimized ET operation [44]. This envelope shaping method, sweet-spot tracking, can provide the best performance for ET-based PAs [29,30,32].…”

Section: Cmos Envelope Tracking Pa With Controlmentioning

confidence: 99%

Design of an Advanced CMOS Power Amplifier

Kim¹,

Park²,

Jin³

2015

Journal of electromagnetic engineering and science

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The CMOS power amplifier (PA) is a promising solution for highly-integrated transmitters in a single chip. However, the implementation of PAs using the CMOS process is a major challenge because of the inferior characteristics of CMOS devices. This paper focuses on improvements to the efficiency and linearity of CMOS PAs for modern wireless communication systems incorporating high peak-toaverage ratio signals. Additionally, an envelope tracking supply modulator is applied to the CMOS PA for further performance improvement. The first approach is enhancing the efficiency by waveform engineering. In the second approach, linearization using adaptive bias circuit and harmonic control for wideband signals is performed. In the third approach, a CMOS PA with dynamic auxiliary circuits is employed in an optimized envelope tracking (ET) operation. Using the proposed techniques, a fully integrated CMOS ET PA achieves competitive performance, suitable for employment in a real system.

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“…There is research about enhancing the efficiency of the supply modulator [5], [6]. The linearity of the ET PA can be improved by the envelope-shaping method [7]- [9] and minimizing the knee effect. Enhanced bandwidth (BW) of the supply modulator [10], [11] can increase the linearity as well.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Intermodulation Distortion of Envelope Tracking Power Amplifier for Linearity Improvement

Moon

Cho

Kim

et al. 2015

IEEE Trans. Microwave Theory Techn.

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An intermodulation distortion of an envelope tracking (ET) power amplifier (PA) is investigated in this paper. For this purpose, the distortion characteristics are simulated based on the inter-connection model between the PA and supply modulator. For the sweet spot tracking ET operation, the fifth-order distortion is the most important one, which is generated by AM-PM nonlinearity. To reduce the distortion, the phase compensation network (PCN) is proposed. The efficiency of the PA is also improved by a properly designed bias circuit. For demonstration purposes, the PA and supply modulator are implemented using an InGaP/GaAs heterojunction bipolar transistor and a 0.18-m CMOS process, respectively. The ET PA is tested at 1.85 GHz using a long-term-evolution signal with 10-MHz bandwidth, a 7.5-dB peak-to-average power ratio, and 16 quadrature amplitude modulation. The ET PA with the proposed PCN and the bias circuit delivers a power-added efficiency of 44.3%, a gain of 23.4 dB, an evolved universal terrestrial radio access adjacent channel leakage ratio of 38.4 dBc, and an error vector magnitude of 1.8% at an average output power of 27 dBm. The multiband characteristics of the proposed ET PA are measured across 1.7-2.0 GHz. These results are achieved without any digitally supported techniques, indicating that the design approach is a promising technique for handset ET PA applications.Index Terms-Adjacent channel leakage ratio (ACLR), bias circuits, efficiency, envelope tracking (ET), intermodulation distortion (IMD), linearity, long-term evolution (LTE), phase compensation network (PCN), power amplifier (PA).

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CMOS Linear Power Amplifier with Envelope Tracking Operation (Invited Paper)

Cited by 20 publications

References 20 publications

Highly Efficient RF Transmitter Over Broad Average Power Range Using Multilevel Envelope-Tracking Power Amplifier

Highly Efficient RF Transmitter Over Broad Average Power Range Using Multilevel Envelope-Tracking Power Amplifier

Design of an Advanced CMOS Power Amplifier

Investigation of Intermodulation Distortion of Envelope Tracking Power Amplifier for Linearity Improvement

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