Self-adaptive biasing technique for microwave bipolar amplifier linearisation

Lau, Kwok Wai; Xue, Quan; Chan, Chi Hou

doi:10.1049/el:20073149

Cited by 4 publications

(4 citation statements)

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“…In previous literatures, the self-adaptive biasing (SAB) circuit has been successfully applied to improve the linearity and efficiency of single-ended PAs [9,10]. In this article, the proposed novel SAB circuit can adaptively control the gate voltage of the peaking PA in a DPA according to the input power.…”

Section: Analysis Of Adaptive Biasing Schemementioning

confidence: 99%

“…The frequency notched UWB microstrip slot antenna with a fractal tuning stub is proposed to achieve frequency notched function [6,7]. Ding et al [8] and Kumar and Sawant [9] have proposed a new UWB fractal antenna by adopting the fractal concept on the CPWfeed. It is reported in literature that the circular and elliptical shape of the antenna is more suitable for ultra-bandwidth (UBW) characteristic in comparison to conventional square monopole antenna.…”

Section: Introductionmentioning

confidence: 99%

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A novel Doherty power amplifier with self‐adaptive biasing network for efficiency improvement

Chen

Xue

2011

Micro & Optical Tech Letters

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maximum intensity of the beam as a function of its position across the channel [Fig. 4]. Figure 4 confirms that the intensity from the shaped beams is drastically improved over the control device (no lens system) and the high intensity cross-channel plateaus are formed in the center of the channel. The plateau of uniform illumination-where the beam is within 5% of the maximum intensity in the center of the channel-is measured to be 10.4-and 6.2-lm long, for the 10-and 3.6-lm lens systems respectively, spanning the center of the channel. These plateau regions are difficult to form as the depth of focus is minimized considerably when focusing a beam to a spot in the channel. However, by using aberrations to warp the Gaussian shape, we have formed large regions where uniform excitation is possible across the entire sample flow. In fact, if the plateaus are measured using the standard depth of focus, it is found that these regions span 26.2 and 14.1 lm for the 10-and 3.6-lm devices, respectively-significant portions of the entire channel, and that intensity varies by 25% from the maximum intensity over this region.It should be noted that there is a noticeable trade-off on the size of the beam waist and the plateau of uniform intensity: the smaller the waist, the smaller the plateau that can be formed, as evidenced by the much smaller region defined by the 3.6-lm device. This is due to the inverse relationship between beam waist and divergence. This is of little consequence because when smaller cells are analyzed, our designs shrink the beam waist to eliminate the occurrence of double detections while the uniform region is kept large enough to accommodate the particle to deviate within the cell flow. A larger maximum intensity is also noted for larger beam waist due to the larger input NA of the lens system allowing greater collection of light from the waveguide. CONCLUSIONSExact formation of ideal beam shapes for cytometric analysis has been demonstrated experimentally. These formed beams are highly desirable in a flow cytometry application because they exploit the ability to control aberrations in the lens design to specifically tailor beam shapes to form as near an ideal a shape for illumination as possible. These bowtie-shaped beams will significantly improve the sensitivity of a photonic-integrated microchip-based flow cytometer by offering an improved area of illumination over previously shown devices [16]. Beam shaping on a photonic-integrated microfluidic flow cytometer is a major step forward to achieving feasible devices for clinical, laboratory, and point-of-care medical applications. ACKNOWLEDGMENTS

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Section: Analysis Of Adaptive Biasing Schemementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A novel Doherty power amplifier with self‐adaptive biasing network for efficiency improvement

Chen

Xue

2011

Micro & Optical Tech Letters

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“…Mok et al [5] have proposed a linearized distributed amplifier with the aid of a parallel diode, but the low average power efficiency still remains a problem. We have introduced a self-adaptive bias network [6], which mainly works on low frequency distortion components, unifies linearity improvement and efficiency enhancement for bipolar amplifiers. Therefore, a selfbiased distributed amplifier, with wideband linearization and adaptive power management, is presented in this letter.…”

Section: Introductionmentioning

confidence: 99%

“…In general, the conventional SPR sensor treats only the real part of the refractive index. Recently, an absorption-based SPR sensor has been studied for measuring the changes in not only the real but also the imaginary parts of the refractive index [2][3][4][5][6]. The behavior of absorption-based SPR responses has been discussed in [3].…”

Section: Introductionmentioning

confidence: 99%

Self‐biased distributed amplifier: Linearity improvement and efficiency enhancement

Lau

Chan

Xue

et al. 2008

Micro & Optical Tech Letters

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A self‐biased distributed amplifier with wideband linearity improvement and efficiency enhancement is presented. With the aid of a self‐adaptive bias network, the location of IMD3 minimum is dynamically manipulated, while the DC bias power of the distributed amplifier is adaptively biased. Experimental two‐tone test successfully demonstrates more than 10 dB and 27% reductions of the first sidelobes and the DC power consumptions are achieved respectively in the proposed design when operating between 900 and 3300 MHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2493–2497, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23711

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A Novel Biasing Technique for Low Adjacent Channel Power in Microwave Power Amplifiers

Lau

Xue

Chan

2007

2007 Asia-Pacific Microwave Conference

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Self-adaptive biasing technique for microwave bipolar amplifier linearisation

Cited by 4 publications

References 5 publications

A novel Doherty power amplifier with self‐adaptive biasing network for efficiency improvement

A novel Doherty power amplifier with self‐adaptive biasing network for efficiency improvement

Self‐biased distributed amplifier: Linearity improvement and efficiency enhancement

A Novel Biasing Technique for Low Adjacent Channel Power in Microwave Power Amplifiers

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