| 1. |
- Sudow, Mattias, 1980, et al.
(författare)
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SiC varactors for dynamic load modulation of high power amplifiers
- 2008
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 29:7, s. 728-730
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Tidskriftsartikel (refereegranskat)abstract
- SiC Schottky diode varactors with a high breakdown voltage, a high tuning ratio, and a low series resistance have been designed and fabricated. These characteristics are particularly necessary for the dynamic load modulation of high power amplifiers (PAs), which is an attractive alternative to other efficiency enhancement techniques. For a SiC Schottky diode varactor with a 50-µm radius fabricated by using a graded doping profile, a breakdown voltage of 40 V, a tuning range of 5.6, and a series resistance of 0.9 O were achieved. The results show the great potential of this type of varactors for the use in the dynamic load modulation of high power amplifiers. © 2008 IEEE.
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| 2. |
- Cao, Haiying, 1982, et al.
(författare)
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Digital Predistortion for High Efficiency Power Amplifier Architectures Using a Dual-input Modeling Approach
- 2012
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 60:2, s. 361-369
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a novel model is proposed for dual-input highefficiency power amplifier (PA) architectures, such as envelope tracking (ET) and varactor-based dynamic load modulation (DLM). Compared to the traditional single-input modeling approach, the proposed model incorporates the baseband supply voltage/load control as an input. This advantage makes the new approach capable to achieve maximized average power-added efficiency (PAE) and minimizedoutput distortion simultaneously. Furthermore, the new approach has shown to be robust towards time misalignment between the RF input and baseband supply voltage/load control signals, and it can be applied with a reduced-bandwidth baseband supply voltage/load control.Experiments have been performed in a varactor-based DLM PAarchitecture to evaluate the new modeling approach. The results show that it can achieve 9 dB and 7 dB better performance than the traditional approaches in terms of adjacent channel leakage ratio and normalized mean square error, respectively. At the same time, the average PAE is maximized. Similar results have been achieved with the proposed model even when reduced-bandwidth baseband loadcontrol signal is used or time misalignment between the RF and baseband load control input signals exists. Although the new approach is only tested with DLM architecture in this paper, it is very general and can be applied to ET architectures as well.
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| 3. |
- Cao, Haiying, 1982, et al.
(författare)
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Linearization of Efficiency-Optimized Dynamic Load Modulation Transmitter Architectures
- 2010
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 58:4, s. 873-881
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a detailed linearization procedure for dynamic load modulation (DLM) transmitter architectures is proposed for the first time. Compared with the conventional single-input/single-output digital predistortion (DPD) approach used with traditional power amplifiers (PAs), the proposed linearization scheme is based on a regular memory DPD in combination with an efficiency-optimized static one-to-two mapping inverse model, which constructs the predistorted input signals to the DLM transmitter. The time-alignment issue, which is very important to this dual-input architecture, is also considered. The proposed technique is demonstrated by a 1-GHz 10-W LDMOS PA that employs a varactor-based tunable matching network. A normalized mean square error of $-{hbox {35 dB}}$, and adjacent channel leakage ratio of $-hbox{43 dBc}$ is achieved, with an average power-added efficiency of 53% for a single-carrier WCDMA signal with 7-dB peak-to-average ratio. Finally, it is shown that the time-alignment sensitivity is relaxed when the proposed linearization scheme is used. This means that the overall complexity of the transmitter implementation can be reduced.
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| 4. |
- Cao, Haiying, 1982, et al.
(författare)
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Time Alignment in a Dynamic Load Modulation Transmitter Architecture
- 2009
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Ingår i: Proceedings of the 39th European Microwave Conference, EuMC 2009, Sept. 29-Oct. 1 2009, Rome. - 9781424447480 ; , s. 1211 - 1214
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Konferensbidrag (refereegranskat)abstract
- A time alignment algorithm is proposed for a dynamic load modulation transmitter architecture. The effect of time mismatch between the RF input and baseband control signal is investigated by experiments, and it is shown that unsynchronized signals can result in severe distortion of the output signal. In this paper, cross correlation and sinc interpolation techniques are applied to estimate and compensate for the sub-sample delay between the RF signal path and the baseband control signal path in the measurement system. The performance of the dynamic load modulation transmitter architecture with accurate time alignment is shown by experimental results. The measurement shows that, the efficiency is greatly affected by time alignment and the spectral regrowth is suppressed by more than 10 dB.
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| 5. |
- Cao, Haiying, 1982, et al.
(författare)
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Time Mismatch Effects in a Dynamic Load Modulation Transmitter Architecture
- 2009
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Ingår i: RF Measurement Technology for State of the Art Production and Design(RFMTC09).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, the effect of time mismatch between the RF input and baseband control signals in a dynamic load modulation transmitter is investigated. Experimental results show that even a small time mismatch between the input signals can result in severe distortion of the output signal.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Fager, Christian, 1974, et al.
(författare)
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High Efficiency Transmitter Using Varactor Based Dynamic Load Modulation
- 2010
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Ingår i: IEEE International Microwave Workshop Series on “RF Front-ends for Software Defined and Cognitive Radio Solutions”. - 9781424457526 ; , s. 37-40
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Konferensbidrag (refereegranskat)abstract
- This paper presents results for a dynamic loadmodulation transmitter where an existing 1 GHz LDMOSpower amplifier is combined with a varactor based tuneableload network to produce a dramatic efficiency improvementfor modulated signals. The transmitter is combinedwith a dedicated linearization method to achieve anaverage PAE of 53% for a WCDMA signal at 7 dB PAPR.The results demonstrate the potential of dynamic loadmodulation for future transmitters combining flexibilityand high efficiency at a low cost.
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