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Switch-mode amplifiers have gained interest in the RF-frequency range, due to their promising features of high linearity and especially high efficiency, compared to conventional class-AB amplifiers. For the operation of a class-S amplifier, it is necessary to convert the arbitrarily modulated RF signal into a pulselength modulated signal. This can be accomplished by delta-sigma modulation or by pulselength...
A Class-S Amplifier architecture theoretically offers high efficiency and nonlinearity resistance. Class-S idea is assumed to base on ideal switches which work in two states - ON and OFF, and these conditions enable nonlinearity resistance. Real implementations are based on switching transistors which suffer on many limits which can contribute to nonlinear effects. This paper includes basic nonlinearity...
This paper presents the design and implementation of a fourth order bandpass delta-sigma modulator (BDSM) for a signal carrier of 450 MHz, sampled at 2 GHz. Designed and fabricated in 0.25 mum SiGe BiCMOS technology the modulator achieves 42,2 dB signal-to-noise ratio (SNR) in 20 MHz bandwidth with sine wave input while consuming 330 mW from a 3.3 V supply. Measurement results show that the circuit...
A novel modulation concept based on Delta-Sigma modulation dedicated for a Class-S Amplifier based on GaN technology is presented. This paper includes system considerations of efficient modulation schemes for GaN switching transistors, which suffer from many limits. The analyses are focused on evaluating the impact of modulation scheme on the switching conditions of the transistors. Moreover practical...
Switching power amplifiers offer the potential for superior efficiencies if used at radio frequencies. However many existing bandpass architectures require a switching frequency four times that of the signal, making implementation difficult. In this paper we propose to use a high-pass sigma-delta modulator to reduce the switching rate to only twice of the signal. We will present a solution to the...
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