Third-order intermodulation reduction by harmonic injection in a TWT amplifier

Wirth, M.; Singh, A.; Scharer, J.E.; Booske, John H.

doi:10.1109/ted.2002.1003754

Cited by 34 publications

(20 citation statements)

References 4 publications

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“…For 3IM injection, the 3IM at 2.00 GHz is generated by mixing the harmonic and the fundamental . The frequency doubler is capable of doubling input frequencies from 1.5-5 GHz and avoids any phase drifts between the fundamental and second harmonic or 3IM frequencies thus resulting in higher suppression than reported in [20].…”

Section: Methodsmentioning

confidence: 99%

“…Suppression of third-order intermodulation or 3IM ( , ) products by harmonic injection in TWTs was first investigated by Sauseng et al [19] who observed a 6-7 dB reduction in the upper and lower 3IMs ( and , respectively, assuming ) at saturation. More recently, 3IM suppression of up to 24 dB has been reported by our group [20]. Second-harmonic injection to control 3IM has also been studied analytically [17] and numerically [14], [17].…”

Section: Introductionmentioning

confidence: 94%

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Second- and Third-Order Signal Predistortion for Nonlinear Distortion Suppression in a TWT

Singh

Scharer

Booske

et al. 2005

IEEE Trans. Electron Devices

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Abstract-The nonlinearity inherent in the traveling wave tube (TWT) amplifier distorts amplified signals and results in reduced efficiency and bandwidth, limiting its use in communication and electronic countermeasure applications. Signal predistortion is an effective technique for suppressing nonlinear distortion in TWTs that provides high suppression and requires simple circuits for implementation. While conventional predistortion linearizers are based on third-order intermodulation (3IM) injection, this paper proposes using second-order (second-harmonic) signal injection in predistortion circuits. A detailed experimental investigation and comparison of second-order versus third-order signal predistortion is presented. It is observed that both schemes result in suppression of up to 30 dB (55 dBc) for the 3IM distortion products. However, experimental results indicate that second-harmonic signal injection performs better than 3IM in suppressing higher order products. The paper also investigates spatial evolution of the wave spectrum along the TWT axis with and without injection, and sensitivity of the suppression to injected signals amplitude, phase and the fundamental frequency.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Second- and Third-Order Signal Predistortion for Nonlinear Distortion Suppression in a TWT

Singh

Scharer

Booske

et al. 2005

IEEE Trans. Electron Devices

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“…The S-MUSE model (25)- (29) may be written in the following vector form that is particularly useful for analysis: (30) where is a 5 2 -dimensional complex vector, is a complex matrix, is a complex 3-tensor, and overdot represents . The detailed specification and indexing of , , and as well as a formula to compute the components of are found in Appendix II.…”

Section: ) Vector Formmentioning

confidence: 99%

“…Under suitable conditions, the S-MUSE model in the vector form (30) can be solved with a series solution where each vector satisfies a differential equation that is a linear system forced by quadratic terms formed by combinations of with . For example, the drive frequencies are in and they combine quadratically to force the differential equation for so as to cause second harmonics in .…”

Section: Analysis Using S-musementioning

confidence: 99%

The multifrequency spectral eulerian (muse) model of a traveling wave tube

Wohlbier

Booske

Dobson

2002

IEEE Trans. Plasma Sci.

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Abstract-We derive from Eulerian electron beam equations the multifrequency spectral Eulerian (MUSE) model, a new onedimensional (1-D) nonlinear multifrequency model of a traveling wave tube (TWT). We also derive from the same equations a Lagrangian "disk" model, LATTE, so that MUSE may be directly compared to a Lagrangian approach. The models are compared to the large signal code Christine 1-D on a set of TWT parameters which are based on a single section of the Hughes 8537H L-band TWT. Aspects of the physics, nonlinearities, and simulation dimensions of the MUSE model are discussed, as well as its relation to the method of collective variables. A simplified MUSE model S-MUSE useful for analysis is also presented and its applications are discussed.

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“…It has been suggested to employ feed forward linearization technique in link to enhance the system performance [1]. There are different methods of linearization [2][3][4][5] but feed forward linearization methods gives better results than all. The feed forward technique is better because it gives a large improvement in IMD3 reduction.. An analysis of 16×10 Gbps WDM system was carried out in [6][7] using the feedforward linearization scheme proposed in [1].…”

Section: Introductionmentioning

confidence: 99%

160 Gbps WDM Transmission System using Linearized SOA with 50 GHz Channel Spacing

Sood¹,

Singh²,

Singh³

2012

IJCA

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In a 16 Channel, 10 Gbps WDM System with Linearized SOA using feed forward linearization technique the effect of reduced channel spacing has been investigated. The basic mechanism of crosstalk is completely independent of the amplifier but it depends on the spectral overlap of adjacent channel. However In this paper it has been validated that using linearized SOA the system can be extended to 120 Km length with channel spacing as small as 50 GHz. The achieved QFactor was 11 at 100km and 4.2 at 120Km.

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Third-order intermodulation reduction by harmonic injection in a TWT amplifier

Cited by 34 publications

References 4 publications

Second- and Third-Order Signal Predistortion for Nonlinear Distortion Suppression in a TWT

Second- and Third-Order Signal Predistortion for Nonlinear Distortion Suppression in a TWT

The multifrequency spectral eulerian (muse) model of a traveling wave tube

160 Gbps WDM Transmission System using Linearized SOA with 50 GHz Channel Spacing

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