A 1.2‐ to 3‐GHz tunable feedforward amplifier using broadband distributed phase shifters

Wu, S. T.; Xiao, Jing; Cha, Honnyong; Jo, Sungjin; Kim, Hongjoon

doi:10.1002/mop.26445

Cited by 2 publications

(7 citation statements)

References 15 publications

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“…This allows a fair comparison between the effect of gain error on the improvement in SDR and ACPR by the FF system. The figures also show that ε α has a much less significant effect on SDR and ACPR, which is evident from Equations (23) and (24). The figures show that as ε β increases, the in-band distortion increases at a much faster rate than out-of-band distortion, and this is evident from the degradation of SDR and ACPR with increasing ε β .…”

Section: Simulation Resultsmentioning

confidence: 76%

“…It is evident from (23) and (24) that this ratio approaches unity as the complex gains are at their optimum values, that is, It is evident from (23) and (24) that this ratio approaches unity as the complex gains are at their optimum values, that is,…”

Section: Signal-to-distortion Ratio Performancementioning

confidence: 96%

“…In the first approach, the amplifier is operated at a point further in the linear region, or equivalently, a point with a large power input back-off (IBO). These complex gains are used to compensate for drifts in the main and error amplifier gains [23][24][25][26][27]. The second approach is to use a linearization technique such as predistortion, feed-forward (FF), feedback, and envelope elimination and restoration approaches [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…The second approach is to use a linearization technique such as predistortion, feed-forward (FF), feedback, and envelope elimination and restoration approaches [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Out of these techniques, FF linearization has been the most attractive approach in OFDM systems because of the wideband nature of the analog circuitry used in manipulating the signals in the FF implementation [21][22][23][24][25][26][27][28]. The operation of the FF techniques is basically concerned with canceling the distortion signal.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Performance of feed‐forward linearizers of power amplifiers in OFDM systems under complex gain errors

Gharaibeh

Al-Zayed

2015

Int J Communication

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Adaptive feed-forward (FF) linearization schemes of power amplifiers provide high distortion cancelation and adjacent channel power ratio (ACPR) reduction. However, FF schemes are very sensitive to imbalances in the circuit parameters used to achieve signal cancelation. In this paper, an FF linearization circuit is analyzed using the orthogonalization of the nonlinear model and considering the effects of complex gain errors in the signal and distortion cancelation loops on the overall performance of the FF linearizer. The analysis enables the effective signal-to-distortion ratio (SDR) and ACPR to be estimated from FF circuit model. It is shown that complex gain errors in the distortion cancelation loop have a more significant effect on in-band distortion than out-of-band distortion, which means that the design of FF linearizers based on ACPR improvement is not optimal.

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Section: Simulation Resultsmentioning

confidence: 76%

Section: Signal-to-distortion Ratio Performancementioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Performance of feed‐forward linearizers of power amplifiers in OFDM systems under complex gain errors

Gharaibeh

Al-Zayed

2015

Int J Communication

View full text Add to dashboard Cite

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“…For different engineering applications, different kinds of tunable phase shifters were proposed using ferrite materials [1][2][3][4], p-i-n diodes [5][6][7], varactor diodes [8][9][10][11], etc. The phase shifters based on ferrite materials usually have large insertion loss and hard to be integrated, while p-i-n diodes are popular in designing digital phase shifters.…”

Section: Introductionmentioning

confidence: 99%

Broadband and wide range tunable phase shifter based on composite right/left handed transmission line

Lin

Zhang

et al. 2012

Journal of Electromagnetic Waves and Applications

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2012) Broadband and wide range tunable phase shifter based on composite right/left handed transmission line, Journal of Electromagnetic Waves and Applications, 26:In this paper, an improved tunable phase shifter with broadband and wide range of the phase shift is proposed. The structure consists of two improved tunable composite right/left handed (CRLH) transmission line (TL) unit cells. A π-shape circuit model is adopted for each unit cell, and its phase characteristic is discussed in detail, based on which a varactor diode parallel to a lumped capacitor in series circuit and two varactor diodes series with other lumped capacitors in shunt circuits are carefully designed to tune the shifted phase as well as the nonignorable lumped inductors. After that, the phase shifter is finally fabricated using two tunable CRLH-TL unit cells. All of the varactor diodes are controlled by only one bias voltage which also leads to a compact size. The simulated and measured results agree well with a continuously tunable phase range more than 170°. The relative bandwidth is 40%, while the input return loss is not large than 10 dB. IntroductionPhase shifters are widely applied to microwave and communication systems, especially in phased array antennas and radars. For different engineering applications, different kinds of tunable phase shifters were proposed using ferrite materials [1-4], p-i-n diodes [5-7], varactor diodes [8-11], etc. The phase shifters based on ferrite materials usually have large insertion loss and hard to be integrated, while p-i-n diodes are popular in designing digital phase shifters. For an analog phase shifter in microwave frequency band, varactor diode-based structures are widely adopted. The capacitance of varactor diode varies continuously when the DC voltage is changed. The quality factor Q is acceptable to reduce loss, hence it is suitable for designing tunable analog phase shifters with good performance, such as compact size, low cost, and broad bandwidth.More recently, metamaterial-based phase shifters have also received considerable attention in both scientific and engineering communities [12][13][14][15][16][17][18][19][20][21][22]. In [12], the tunable phase shift reaches 342°by cascading 13 left-handed metamaterials (LHMs) units with operation frequencies from 8 to 10 GHz. In [14], a phase shifter is cascaded by four LHMs units with an adjustable phase ranging more than 150°, but the relative bandwidth is less than 20%. In [15], a digital phase shifter is fabricated by cascading five composite right/left handed (CRLH) transmission line (TL) unit cells. The relative bandwidth is only 10% at X-band. In

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A 1.2‐ to 3‐GHz tunable feedforward amplifier using broadband distributed phase shifters

Cited by 2 publications

References 15 publications

Performance of feed‐forward linearizers of power amplifiers in OFDM systems under complex gain errors

Performance of feed‐forward linearizers of power amplifiers in OFDM systems under complex gain errors

Broadband and wide range tunable phase shifter based on composite right/left handed transmission line

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