| 1. |
- ÖZEN, MUSTAFA, 1984, et al.
(författare)
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Linearization Study of a Highly Efficient CMOS-GaN RF Pulse Width Modulation Based Transmitter
- 2012
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Ingår i: European Microwave Conference. - : IEEE. ; , s. 136-139
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Konferensbidrag (refereegranskat)abstract
- This paper studies linearity of a 2 GHz, 10 Watt peak output power RF pulse width modulation (RF-PWM) based transmitter. The transmitter incorporates a tunable load network class-E PA as the final output stage. The tunable load network enables dynamic optimization of the class-E along with the duty cycle resulting in high efficiency over a wide range of output power levels. A digital predistiortion based linearization scheme is proposed to enhance the linearity of the transmitter. After linearization, the transmitter exhibits an adjacent channel power ratio (ACPR) of -45 dBc with a 3.84 MHz, 6.7 dB peak-to-average power ratio (PAPR) W-CDMA signal. The average drain efficiency of the GaN HEMT output stage is 67% and the total transmitter efficiency is 54%.
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| 2. |
- Andersson, Christer, 1982, et al.
(författare)
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A packaged 86 W GaN transmitter with SiC varactor-based dynamic load modulation
- 2013
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Ingår i: 43rd European Microwave Conference, EuMC 2013 - Held as Part of the 16th European Microwave Week, EuMW 2013, Nuremberg, Germany, 7-10 October 2013. - 9782874870316 ; , s. 283-286
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Konferensbidrag (refereegranskat)abstract
- Output power scaling based on class-J dynamic load modulation (DLM) theory is used to design an unprecedentedly high power microwave transmitter with varactor-based DLM functionality. Matching networks are realized on high dielectric constant substrates in order to reduce the form factor. The fully matched DLM PA incorporates a 24-mm GaN HEMT powerbar and a stack of four SiC varactors, all fit into a CuW package (40 mm × 20 mm). Peak output power is reconfigurable by changing the drain voltage, while retaining the DLMeffect. Under pulsed conditions at 40 V the PA delivers a peak power of 86 W at 2.14 GHz. Efficiency enhancement by DLM is 10-15 percentage-units at 6 dB output power back-off (OPBO). Employing digital predistortion (DPD) with a vector switched generalized memory polynomial (VS-GMP) the ACLR is -46 dBc at an average output power of 17 W and a drain efficiency of 34%. These results prove the potential for high output power levels in varactor-based DLM transmitters.
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| 3. |
- Asbeck, Peter M., et al.
(författare)
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Power Amplifiers for mm-Wave 5G Applications: Technology Comparisons and CMOS-SOI Demonstration Circuits
- 2019
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 67:7, s. 3099-3109
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Tidskriftsartikel (refereegranskat)abstract
- A review is presented of key power amplifier (PA) performance requirements for millimeter-wave 5G systems, along with a comparison of the potential of different semiconductor technologies for meeting those requirements. Output power, efficiency, and linearity considerations are highlighted, and related to semiconductor material characteristics. Prototype 5G PAs based on silicon technologies are then reviewed, with primary emphasis on CMOS-SOI. Stacked FET PAs based on nMOS and pMOS for 28-GHz operation are presented, along with outphasing and Doherty amplifiers. Peak power-added efficiency (PAE) up to 46% is demonstrated for a two-stack pMOS amplifier with saturation power (Psat) above 19 dBm. PAE at 6 dB backoff above 27% is shown for an nMOS Doherty PA with 22-dBm Psat. Operation with 64QAM OFDM modulation signals at 800-MHz bandwidth is reported, with up to 13-dBm output power and more than 17% PAE, without the use of digital predistortion. Future challenges for PA development are discussed.
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| 4. |
- Chani Cahuana, Jessica, 1988, et al.
(författare)
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Digital Predistortion Parameter Identification for RF Power Amplifiers Using Real-Valued Output Data
- 2017
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Ingår i: IEEE Transactions on Circuits and Systems II: Express Briefs. - 1549-7747 .- 1558-3791. ; 64:10, s. 1227-1231
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Tidskriftsartikel (refereegranskat)abstract
- This brief presents a novel digital predistortion (DPD) parameter identification technique that requires only the acquisition of either the in-phase (I) or the quadrature (Q) component of the power amplifier (PA) output signal. To this end, an approach that allows us to estimate the parameters of a model using only one of the IQ components of the model output is presented. Based on experimental results, it is shown that the proposed real-valued measurements based technique can offer similar linearization capabilities as its complex-valued counterparts. The experimental results also indicate that the proposed technique can be used in combination with other techniques that focus on reducing the speed of analog-to-digital converters (ADCs)
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| 5. |
- Fager, Christian, 1974, et al.
(författare)
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Design of linear and efficient power amplifiers by generalization of the Doherty theory
- 2017
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Ingår i: Proceedings of the 2017 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications. - 9781509034574 ; , s. 29-32
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Konferensbidrag (refereegranskat)abstract
- The Doherty power amplifier (PA) is now established as one the most widely adopted architectures for enhancement of energy efficiency in wireless communication transmitters. More than 80 years after its invention, most of today's implementations still rely on the original circuit topology. This paper describes a new Doherty solution continuum that is revealed when the original λ/4 combiner is replaced by a generic, analytically derived, lossless combiner network. As a result, novel Doherty PA solutions that in practice are both more efficient and more linear are enabled. A variety of practical design examples are included to illustrate how the presented techniques can enable enhanced performance in both traditional and emerging mm-wave 5G wireless communication transmitter applications.
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| 6. |
- Hallberg, William, 1988, et al.
(författare)
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A class-J power amplifier with varactor-based dynamic load modulation across a large bandwidth
- 2015
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Ingår i: 2015 IEEE MTT-S International Microwave Symposium, IMS 2015. - 9781479982752
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Konferensbidrag (refereegranskat)abstract
- A novel class-J operated power amplifier (PA) utilizing varactor-based dynamic load modulation is presented. It is theoretically shown that the proposed PA can maintain high average efficiency across more than 35% RF bandwidth by means of a purely reactive load modulation after the transistor output capacitance. The theory is experimentally verified by a 15 W GaN HEMT PA operating from 1.80 to 2.20 GHz, using SiC varactors as dynamically tunable load elements. In the band, the PA presents a power added efficiency (PAE) higher than 39% at 6 dB output power back-off. For a 3.84 MHz W-CDMA signal with 6.7 dB peak to average power ratio, an average PAE higher than 39% and an adjacent channel leakage ratio below -45.8 dBc are obtained across the entire band after linearization.
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| 7. |
- Hallberg, William, 1988, et al.
(författare)
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A Doherty Power Amplifier Design Method for Improved Efficiency and Linearity
- 2016
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 64:12, s. 4491-4504
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Tidskriftsartikel (refereegranskat)abstract
- A novel Doherty power amplifier (PA) design method enabling high efficiency and high linearity simultaneously is proposed. The output combiner network is treated as a black box, and its parameters, together with the input phase delay, are solved based on given transistor characteristics and design requirements. This opens for new PA solutions with nonconventional Doherty behavior. The increased design space enables new tradeoffs in Doherty PA designs, including solutions with both high efficiency and high linearity simultaneously. A method utilizing the new design space is developed. For verification, a 20-W 2.14-GHz symmetrical gallium nitride high electron mobility transistors Doherty PA is fabricated and measured. The PA obtains an average power added efficiency of 40% and an adjacent power leakage ratio of -41 dBc without any linearization for an 8.6-dB peak to average power ratio 10-MHz-long term evolution signal, at an average output power of 35.5 dBm.
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| 8. |
- Hallberg, William, 1988, et al.
(författare)
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Characterization of linear power amplifiers for LTE applications
- 2018
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Ingår i: PAWR 2018 - Proceedings 2018 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications. - 9781538612897 ; 2018-January, s. 32-34
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Konferensbidrag (refereegranskat)abstract
- This paper compares the performance of and analyzes the linearity metrics with different signals for two linear PAs: A single-ended class-AB PA and a linear Doherty PA (DPA). Both PAs utilize the 6 W GaN HEMT CGH40006P at a design frequency of 3 GHz for the class-AB PA and 3.5 GHz for the DPA. Different linearity metrics are studied for a 5-MHz spaced two-tone signal and a 5-MHz Long Term Evolution signal. The DPA has a power added efficiency of 40% whereas the class-AB PA shows 27% given a-40 dBc linearity constraint on the closest adjacent channel (ACPRi). The class-AB PA, however, exhibits better linearity in terms of ACPR2. It is additionally shown that the trends of the linearity metrics for the different signals differ for the two architectures.
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| 9. |
- Hallberg, William, 1988, et al.
(författare)
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Current scaled Doherty amplifier for high efficiency and high linearity
- 2016
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Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781509006984 ; 2016-August, s. Art. no. 7540185-
-
Konferensbidrag (refereegranskat)abstract
- In this paper, a novel Doherty power amplifier (PA) design method that enables high efficiency and high linearity simultaneously is developed. The output combiner network parameters are solved to satisfy boundary conditions required for high efficiency, and linear gain and phase responses. The proposed method is experimentally verified by a 2.14 GHz prototype PA, fabricated using two identical 15 W GaN HEMT devices. For a 8.6 dB peak to average power ratio 10 MHz LTE signal, the PA presents an average power added efficiency of 40%, and an adjacent power leakage ratio of -41 dBc without any linearization.
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| 10. |
- Lai, Szhau, 1985, et al.
(författare)
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Low Phase Noise GaN HEMT Oscillators With Excellent Figures of Merit
- 2014
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Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 24:6, s. 412-414
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents guidelines for the design of low phase noise oscillators in GaN high electron mobility transistor (HEMT) technology. The design starts from bias-dependent low-frequency (LF) noise measurements. Oscillator topology and bias point are then chosen for operation in regions where LF noise is low. The best LF noise properties are obtained for low drain voltage and current. Thus, the low phase noise can be achieved at low dc power which also means that power normalized phase noise figure of merit (FOM) will be good.
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