Miniaturisation of combline filters for switched-mode power amplifier systems

Serebryakova, Elena; Blau, Kurt; Hein, Matthias

doi:10.5194/ars-6-125-2008

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…This solution enables reduction physical length of transmission line element and makes filter geometrically more compact. Furthermore coaxial resonator realizations (without any additional dielectric materials) offer Q-factors up to 2000 with significant attenuation of higher order resonances [3], [4]. Moreover Class-S architecture based on CSCD topology requires differential termination with real impedance in passband and short circuit termination out of band.…”

Section: Combline Filter (Clf)mentioning

confidence: 99%

Modulation and filter test procedure for RF Class-S Power Amplifier architecture

Samulak

Serebryakova

Fischer

et al. 2009

2009 Asia Pacific Microwave Conference

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2El e n a . Se r e b rya kova @ Tu -I l me na u . d e Abstract-A Class-S Power Amplifier architecture theoretically offers high efficiency operation and seems to be an attractive alternative for classical PAs architecture. Switching mode PA principle assumes operation on digital, single -bit Delta-Sigma (b.~) modulated signals which contain significant level of outof-band noise. As a result, switching concept requires very narrowband, low loss filter solution which can handle with high power signals. Complexity of Class-S idea and operation on different types of signals require definitions of new analyze and test procedures which are valid for switching mode PAs. Presented work describes spectral measurement tests for b.m odulated signals and output reconstruction filter. Moreover work defines filter requirements for output of the 3 types of modulation based on b.~scheme which can be engaged in Class-SPA. Analyses and measurements were performed at the carrier frequency of 450 MHz.

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Section: Combline Filter (Clf)mentioning

confidence: 99%

Modulation and filter test procedure for RF Class-S Power Amplifier architecture

Samulak

Serebryakova

Fischer

et al. 2009

2009 Asia Pacific Microwave Conference

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“…The resulting electrical as well as geometrical constraints for the design of a filter for a class-S power amplifier system can be satisfied by comb-line filters (CLF) [2], although specific adaptations have to be made. Fig.…”

Section: Introductionmentioning

confidence: 99%

High-power filters for switched-mode power amplifier systems

Serebryakova

Trabert

Blau

et al. 2009

2009 IEEE Radio and Wireless Symposium

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This paper presents the design and experimental characterisation of a coaxial comb-line band-pass filter for a switched-mode power amplifier (class-S), for an operating frequency of 450 MHz. The class-S amplifier architecture is laid out for very efficient amplification and high-power operation. Both requirements present challenges for the design of the reconstruction filter terminating the final stage. According to measurement results, an initially developed filter provided a bandwidth of 26 MHz, an insertion loss of 0.55 dB, and a second pass-band only at 2.8 GHz. The maximum input power handled by the filter amounted to 54 W, staying below the requirement. This power level was limited by electrical breakdown. Therefore, a highpower adaptation was devised and realised in an improved design subsequently. The resulting filter not only provided an even lower insertion loss of 0.37 dB but also handled more than 300 W input power. I. INTRODUCTIONRecently, the interest in increasing the power-added efficiency (PAE) of RF-and microwave power amplifiers in the final stage of a transmitter chain for mobile communications has grown significantly. The most efficient microwave power amplifiers operate in a switching mode, e.g., in class-S operation for input signals of arbitrary waveform. A switched-mode class-S power amplifier can provide high efficiency (> 70%) and, at the same time, high linearity, which makes it very attractive for, e.g., applications in mobile communications. Such an amplifier system consists of the following three basic building blocks, as indicated by Fig. 1 [1]: 1. A one-bit modulator, e.g., a pulse-length modulator (PLM) or a band-pass delta-sigma modulator (BDSM), maps the information contained in the high-frequency carrier signal into a train of pulses of variable length but constant amplitude. 2. A switching amplifier, possibly consisting of a driver and a push-pull final stage, provides the desired amplification by switching a bias source. 3. A band-pass filter is required for the reconstruction of the amplified signal. The output signal of the final stage of a class-S power amplifier includes noise-type signals from previous stages over a very broad frequency range. For the case of a BDSM, the output signal has a noise-like behaviour, whereas a PLM creates parasitic harmonics with significant power levels. Therefore, the band-pass filter has to provide not only extremely low insertion loss -an insertion loss of 1 dB reduces the overall efficiency by as much as 20 % -

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Miniaturisation of combline filters for switched-mode power amplifier systems

Cited by 2 publications

References 4 publications

Modulation and filter test procedure for RF Class-S Power Amplifier architecture

Modulation and filter test procedure for RF Class-S Power Amplifier architecture

High-power filters for switched-mode power amplifier systems

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