A 2GHz GaN Class-J power amplifier for base station applications

The design and implementation of a high efficiency Class-J power amplifier (PA) for base station applications is reported. A commercially available 10 W GaN HEMT device was used, for which a large-signal model and an extrinsic parasitic model were available. Following Class-J theory, the needed harmonic terminations at the output of the transistor were defined and realised. Experimental results show good agreement with simulations verifying the class of operation. Efficiency above 70% is demonstrated with an output power of 39.7 dBm at an input drive of 29 dBm. High efficiency is sustained over a bandwidth of 140 MHz.The design and implementation of a high efficiency Class-J power amplifier (PA) for base station applications is reported. A commercially available 10 W GaN HEMT device was used, for which a large-signal model and an extrinsic parasitic model were available. Following Class-J theory, the needed harmonic terminations at the output of the transistor were defined and realised. Experimental results show good agreement with simulations verifying the class of operation. Efficiency above 70% is demonstrated with an output power of 39.7 dBm at an input drive of 29 dBm. High efficiency is sustained over a bandwidth of 140 MHz

Evaluation of commercial GaN HEMTs for pulsed power applications

A non-conformally invariant coupling between the inflaton and the photon in the minimal Lorentz-violating standard model extension is analyzed. For specific forms of the Lorentz-violating background tensor, the strong-coupling and back-reaction problems of magnetogenesis in de Sitter inflation with scale $${\sim }10^{16}\,\hbox {GeV}$$ are evaded, the electromagnetic-induced primordial spectra of (Gaussian and non-Gaussian) scalar and tensor curvature perturbations are compatible with cosmic microwave background observations, and the inflation-produced magnetic field directly accounts for cosmic magnetic fields

A fundamental limit on the performance of geometrically-tuned planar resonators

Geometric frequency tuning in planar electromagnetic resonators is common in many applications. It comes, however, at a penalty in the resonance quality, Q0. The literature traces the causes of such penalty often in terms of the shortcomings in the added elements and materials, which were used to achieve the tuning. In this paper, however, it is shown that another underlying source of quality degradation exists at the fundamental geometric level. This source, unlike other added sources of degradation during tuning, will always exist (even before tuning takes place) and will rely on the “modal areas” of the geometric modifications made to host the tuning mechanism. Hence, it forms an upper bound to the performance that can be achieved from a geometically-tuned planar resonator, carries an important insight to resonator design in general, and significantly helps in the understanding of the problem of geometric tuning in particular. We present the electromagnetic theory behind this limit and canonically demonstrate it using practical microwave resonator examples. The theory, finite-element method simulation, and experiment results are presented and good agreement is observed. It is shown that incorporating such understanding into the design process of tunable planar resonators can help optimize their performance against a given set of design requirements. Furthermore, the presented theory provides a useful electromagnetic model as a tool for estimating Q0 for geometrically modified or irregular metal patches and planar resonators in general, to assist analysis, and design at any wavelength or application. The theory also asserts that, under a given mode, a planar resonator will always have its maximum Q0 before introducing any internal subtractive geometric modifications (e.g., cuts, apertures, or slits) to its original shape.Geometric frequency tuning in planar electromagnetic resonators is common in many applications. It comes, however, at a penalty in the resonance quality, Q0. The literature traces the causes of such penalty often in terms of the shortcomings in the added elements and materials, which were used to achieve the tuning. In this paper, however, it is shown that another underlying source of quality degradation exists at the fundamental geometric level. This source, unlike other added sources of degradation during tuning, will always exist (even before tuning takes place) and will rely on the “modal areas” of the geometric modifications made to host the tuning mechanism. Hence, it forms an upper bound to the performance that can be achieved from a geometically-tuned planar resonator, carries an important insight to resonator design in general, and significantly helps in the understanding of the problem of geometric tuning in particular. We present the electromagnetic theory behind this limit and canonically demonstrate it using practical microwave resonator examples. The theory, finite-element method simulation, and experiment results are presented and good agreement is observed. It is shown that incorporating such understanding into the design process of tunable planar resonators can help optimize their performance against a given set of design requirements. Furthermore, the presented theory provides a useful electromagnetic model as a tool for estimating Q0 for geometrically modified or irregular metal patches and planar resonators in general, to assist analysis, and design at any wavelength or application. The theory also asserts that, under a given mode, a planar resonator will always have its maximum Q0 before introducing any internal subtractive geometric modifications (e.g., cuts, apertures, or slits) to its original shape

Throughput improvement on bidirectional Fano algorithm

Recently, we introduced a bidirectional Fano algorithm (BFA) [10] which can achieve much higher decoding throughput compared to the regular unidirectional Fano algorithm (UFA), especially at low signal-to-noise-ratio (SNR). However, the decoding throughput improvement of the conventional BFA with respect to the UFA reduces as the SNR increases and converges to 100% at high SNR. In this paper, two parameters in the BFA, which are known as the number of merged states (NMS) and the threshold increment value Δ, are exploited to improve the decoding throughout of the conventional BFA. The improved BFA can achieve much higher decoding throughput compared to the UFA and the conventional BFA, especially at high SNR. For example at Eb/N0=5dB, the throughput improvement achieved by the improved BFA is about 280% compared to the UFA and about 80% compared to the conventional BFA, and its computational complexity is only 4% of the Viterbi algorithm.Recently, we introduced a bidirectional Fano algorithm (BFA) [10] which can achieve much higher decoding throughput compared to the regular unidirectional Fano algorithm (UFA), especially at low signal-to-noise-ratio (SNR). However, the decoding throughput improvement of the conventional BFA with respect to the UFA reduces as the SNR increases and converges to 100% at high SNR. In this paper, two parameters in the BFA, which are known as the number of merged states (NMS) and the threshold increment value Δ, are exploited to improve the decoding throughout of the conventional BFA. The improved BFA can achieve much higher decoding throughput compared to the UFA and the conventional BFA, especially at high SNR. For example at Eb/N0=5dB, the throughput improvement achieved by the improved BFA is about 280% compared to the UFA and about 80% compared to the conventional BFA, and its computational complexity is only 4% of the Viterbi algorithm

Bidirectional fano algorithm for high throughput sequential decoding

Various techniques, such as bidirectional search, have been employed in sequential decoding to reduce the decoding delay. In this paper, a idirectional Fano algorithm (BFA) is proposed, in which a forward decoder (FD) and a backward decoder (BD) search in the opposite direction simultaneously. It is shown that the proposed BFA can reduce the average decoding delay by at least 50% compared to the unidirectional Fano algorithm (UFA). Due to the reduction in the variability of the computational effort by using bidirectional search, there is even higher decoding throughput improvement at low signal-to-noise ratio (SNR). For example at Eb/No=3dB, there is 300% throughput improvement by using the BFA decoding compared to the conventional UFA decoding. The proposed BFA decoding technique can be employed in very high throughput wireless communication systems with low hardware complexity and power consumption.Various techniques, such as bidirectional search, have been employed in sequential decoding to reduce the decoding delay. In this paper, a bidirectional Fano algorithm (BFA) is proposed, in which a forward decoder (FD) and a backward decoder (BD) search in the opposite direction simultaneously. It is shown that the proposed BFA can reduce the average decoding delay by at least 50% compared to the unidirectional Fano algorithm (UFA). Due to the reduction in the variability of the computational effort by using bidirectional search, there is even higher decoding throughput improvement at low signal-to-noise-ratio (SNR). For example at Eb/No=3dB, there is 300% throughput improvement by using the BFA decoding compared to the conventional UFA decoding. The proposed BFA decoding technique can be employed in very high throughput wireless communication systems with low hardware complexity and power consumption