Reconfigurable GaN Digital Tx Applying BST Bandpass Filter

Wentzel, Andreas; Schuster, Christian; Jakoby, Rolf; Maune, Holger; Heinrich, W.

doi:10.1109/mwsym.2019.8701010

Cited by 2 publications

(11 citation statements)

References 8 publications

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“…The tuned MSLP PA accomplishes a suppression of the 2 th and 3 rd harmonics above 36.9 dBc and 33 dBc, respectively. The suppression of the bandpass based PA in [23] shows a lower suppression of the 6 th − 9 th harmonics below 60 dBc, compared to the MSLP version. The 2 nd and 3 rd harmonic are suppressed by 32.9 dBc and 29.8 dBc, respectively.…”

Section: Tunable Pa System: Spectral Behaviormentioning

confidence: 90%

“…In [45], the frequency tunability is greatly increased to 87 % by parallelizing continuously tunable filters at the cost of higher complexity, size and insertion loss. Filters based on BST varactors [23], [40], [46]- [50] achieve tunability up to 40 %. Even the continuously tunable 1 st order BST bandpass filter in [23] shows only a limited tunability of 39 % with losses between 0.6 dB to 2.5 dB.…”

Section: Concept For Tunable Output Filtersmentioning

confidence: 99%

“…Filters based on BST varactors [23], [40], [46]- [50] achieve tunability up to 40 %. Even the continuously tunable 1 st order BST bandpass filter in [23] shows only a limited tunability of 39 % with losses between 0.6 dB to 2.5 dB. The drawback of tunable bandpass filters is their strong dependence on the resonator tunability of the underlying tunable element, which can only be overcome by increasing complexity.…”

Section: Concept For Tunable Output Filtersmentioning

confidence: 99%

“…The untuned case represents the output spectrum only filtered by the fixed lowpass filter, since the tunable stopbands are tuned to frequencies other than the harmonics. For comparison, the output spectrum of the reconfigurable PA based on a tunable bandpass from [23] is presented. The spectra are shown in the upper graphs in Figure 14, the lower one presents a comparison of the presented spectra from the fundamental f c up to the 6 th order harmonics.…”

Section: Tunable Pa System: Spectral Behaviormentioning

confidence: 99%

“…All published digital PA realizations in the microwave domain did not apply any tunable filter concepts to make the amplifier reconfigurable for future CR and SDR applications. Recently, in [23] we presented the first continuously tunable digital power amplifier using a 1 st -order bandpass (BP) filter as output stage, whereby the inherent advantages of the digital PA approach concept could be preserved. That work reveals a tunable operating frequency between 1.1 GHz to 1.8 GHz, but shows low suppression of the harmonic power peaks, which reduces the signal quality.…”

Section: Introductionmentioning

confidence: 99%

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Concept for Continuously Tunable Output Filters for Digital Transmitter Architectures

et al. 2019

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This paper presents a novel output filter approach for continuously frequency-tunable digital power amplifiers, suitable for future seamless and band-less applications in 5G, e.g. for cognitive radios (CR). The presented tunable output filter is based on a multi-bandstop lowpass response to regenerate the original microwave signal at the output of the digital amplifier stage by suppressing unwanted frequency components. Compared to conventional tunable bandpass solutions, it offers higher tunability, higher linearity, good power handling capability and moderate losses especially around the carrier frequency. A tunable power amplifier (PA) demonstrator consisting of a 4-stage digital GaN PA MMIC and the novel tunable filter, is designed and fabricated for a carrier frequency range from 1 GHz to 3 GHz. Tunability is achieved by using commercial barium strontium titanate (BST) varactors. Small signal measurements were performed to evaluate tunability and suppression capabilities of the novel filter structure, which reveal a frequency tunability of 67 % with a suppression level of at least 13 dB for the undesired frequency components. The proposed filter structure exhibits a linearity over the tuning range with an OIP3 between 66 dBm to 70 dBm and high power handling capability. Finally, the performance analysis of the tunable PA demonstrator shows an peak efficiency of 70 %. Due to frequency limitations of the used PA stage, the efficiency slowly degrades to 20 % at the upper frequency band edge. Simultaneously, the output power varies between 27 dBm to 31 dBm.INDEX TERMS Tunable circuits and devices, microwave power amplifiers, digital amplifiers, GaN, tunable filters, BST.

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Section: Tunable Pa System: Spectral Behaviormentioning

confidence: 90%