A Linearized 2.4 GHz CMOS Doherty RF Power Amplifier for Wireless Communication Systems (original) (raw)
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Lautech Journal of Engineering and Technology, 2005
I This paper gives e brief description of linear modulation schemes and how they are more etlicient for daa communicalion. Different classes of RF. power ampliJiers with respect to their elficiencies are also discussed, ss weII as different linearisation techniques presently in use and those at the Research and Developmental stage. This paper illustrutes with *amples how more elJicient modulation schemes and morc eJlicient classes of RF power amplifrerc cqn be adopted for use in data communications, il the inherent probkm of spectral spreading, whlch results from non-linesr ourput of RF power amplifiers at the front end of devices can be effeuively hsndled.
A Novel Power Amplifier Linearization Method for Handset Applications
ICIECA 2013, 2013
A new circuit concept to improve the maximum linear output power of a Universal Mobile Telecommunication System (UMTS) power amplifier (PA) is introduced in this paper. The proposed circuit consists of an analog pre-distorter (APD) integrated at the input of a class B amplifier. The proposed APD extends the maximum linear output power of the PA to 28dBm with corresponding power added efficiency (PAE) of 52.3%. Simulation result shows that at 1.95GHz, PA has a worst case adjacent channel leakage ratio (ACLR) of -36dBc at output power of 28dBm. With a respective input and output return losses of -27.6dB and -13.2dB, the PA’s power gain is simulated to be 33.3dB while exhibiting an unconditional stability characteristic from DC to 3GHz. The monolithic microwave integrated circuit (MMIC) power amplifier (PA) is designed in 2μm InGaP/GaAs process. The proposed APD technique serves to be a good solution to improve the maximum linear output power of the UMTS PA without sacrificing other critical performance metrics.
Digital linearizer for RF amplifiers
… , IEEE Transactions on, 1997
Broadcast technology is at the beginning of a new era. It is characterized by the intensive use of the most advanced digital modulations formats (8VSB, QAM, OFDM) in combination with high power RF amplifiers. To date the linearity required for these digital formats has only been accomplished in cumbersome low efficiency class A amplifier or even more cumbersome feed-forward systems. A potentially more efficient and cost effective approach is the combination of non linear power amplifiers and a predistortion technique capable of compensating for the non linear amplifiers. Digital predistortion will provide a highly linear output and improved efficiency. Itelco has developed a digital adaptive base band predistorter to provide for improved performance and cost. The technique is independent of the modulation type, the output frequency, or the signal bandwidth. Furthermore the capability of automatic adaptive predistortion to compensate for the environment (temperature, power supply variations, aging ,and even operation during replacement of a faulty module) is highly desirable.
A novel linearization technique for linear/pseudo-linear RF CMOS power amplifiers
2004
Abstract A novel linearization technique for linear and pseudo-linear CMOS power amplifiers (PAs) is presented. The proposed technique uses the third-order harmonic of the PA output to generate a signal, which compensates the nonlinear component at the fundamental frequency of the PA output. The reconstructed signal is then subtracted from the output of the PA to cancel out its nonlinear component.
IEEE Microwave Magazine, 2000
Concurrent Linearization ith the explosive growth of the smartphone and tablet markets, wide bandwidth voice and data communication have become ubiquitous. Users expect to use their wireless portable phone/computing devices at any place and at any time. Furthermore, with the today's economy of scale, yesterday's high-performance devices are today's entry-model devices. To make possible this global wide-bandwidth wireless communication and networking while handling the increasing number of users, new wireless communication standards based on high bandwidth efficiency protocols such as orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA) have been developed to meet the user capacity requirements. These new communication standards have, however, placed very challenging demands on the RF front-end specifications in terms of bandwidth and power efficiency for both hand-held devices and base stations. Indeed, a characteristic of OFMD and CDMA signals is that they feature very high peak to average power ratios (PAPR), typically on the order of 10 dB even after crest factor reduction techniques or softclipping. Thus, for example, an 80 W average power base-station power amplifier (PA) should be able to also amplify linearly outburst, with 800 W instantaneous peak power. Special RF amplifiers are then needed to amplify such signals with large PAPR while providing high average power efficiency. However, power efficiency in PA operation comes in practice at the cost of increased nonlinearities. As is well known, nonlinearities lead not only to inband signal distortion but also to outband spectral regrowth, which are strictly regulated. A provider cannot pollute the band of a competitor. Thus, linearization techniques are used to linearize the amplifiers and reduce the inband signal distortion and outband spectral regrowth to acceptable levels.
2007
Digital predistortion of a baseband signal is a well-known method of power amplifier (PA) linearization used to reduce adjacent channel interference (ACI) in a non constant envelope modulation system. This paper discusses the application of adaptive digital baseband predistortion linearization to radio frequency (RF) power amplifiers (PAs) that exhibit memory effects. This technique is a highly cost- effective way to linearize Power amplifiers (PAs), but most existing architectures assume that the PA has a memoryless nonlinearity. For wider bandwidth applications such as wideband code-division multiple access (WCDMA) or wideband orthogonal frequency-division multiplexing (W- OFDM), PA memory effects can no longer be ignored. In this paper a new technique for adaptation of digital predistorter that considers memory effects in power amplifiers is proposed. This method is a combination of two techniques, memory polynomial predistortion and slope-dependent method. This new technique is validated by using a 1.9 GHz 60 W LDMOS power amplifier and various signals such as 2- carrier CDMA and 3-carrier CDMA.
Frequency-Selective Predistortion Linearization of RF Power Amplifiers
IEEE Transactions on Microwave Theory and Techniques, 2000
This paper presents a frequency-selective RF vector predistortion linearization system for RF multicarrier power amplifiers (PAs) affected by strong differential memory effects. Differential memory effects can be revealed in two-tone experiment by the divergence for increasing tone-spacing of the vector Volterra coefficients associated with the lower and upper intermodulations tones. Using large-signal vector measurement with a large-singal network analyzer, a class-AB LDMOS RF PA is demonstrated to exhibit a strong differential memory effect for modulation bandwidth above 0.3 MHz. New frequency-selective RF and baseband predistortion linearization algorithms are proposed to separately address the linearization requirements of the interband and inband intermodulation products of both the lower and upper sidebands. Theoretical verification of the algorithms are demonstrated with MATLAB simulations using a Volterra/Wiener PA model with memory effects. The baseband linearization algorithm is next implemented in a field-programmable gate array and experimentally investigated for the linearization of the class-AB LDMOS PA for two carrier wideband code-division multiple-access signals. The ability of the algorithm to selectively linearize the two interband and four inband intermodulation products is demonstrated. Adjacent channel leakage ratio of up to 45 dBc for inband and interband are demonstrated experimentally at twice the typical fractional bandwidth.
Adaptive digital baseband predistortion for RF power amplifier linearization
High Frequency Electronics, 2006
Power amplifiers (PAs) are vital components in many communication systems. To be transmit-ted wirelessly, a signal must be amplified with high fidelity so as to account for attenuation through the channel or propagation medium. The linearity of a PA response constitutes ...
Adaptive Lineariser for RF Wideband Power Amplifier
International Journal of Advances in Computing and Information Technology, 2012
The high power amplifiers (HPAs) for CDMA and OFDM telecommunication systems need to be highly linear. However in practise, the response of HPA is non-linear which introduces distortion in signals being amplified. This response can be made linear using various linearization techniques. In this paper, an adaptive pre-distortion based linearization technique is introduced. It is based on adding pre-distortions into signals, which will result in cancellation of non-linear distortions appearing in power amplifier. The characteristics of this non-linear adaptive lineariser are represented by an analogue polynomial. In this paper, the coefficients of this polynomial are adjusted automatically in a manner that the output of lineariser when fed to an amplifier, the final output becomes error free and the whole system behaves like a linear amplifier. This helps reducing the distortion in power amplifiers, resulting in a better linearised output.