Jiyoun Lim et al. 377 A novel power amplifier for a polar transmitter is proposed to achieve better spectral performance for a wideband envelope signal. In the proposed scheme, 2-bit sigma-delta (ΣΔ) modulation of the envelope signal is introduced, and the power amplifier configuration is modified in a binary form to accommodate the 2-bit digitized envelope signals. The 2-bit ΣΔ modulator lower...

This paper presents and discusses two possible real-time digital predistortion (DPD) architectures suitable for envelope tracking (ET) power amplifiers (PAs) oriented at a final computationally efficient implementation in a field programmable gate array (FPGA) device. In ET systems, by using a shaping function is possible to modulate the supply voltage according to different criteria. One possi...

The discrimination of the depth of amplitude modulation of a signal carrier frequency can be disrupted by the presence of other modulated carriers (maskers), an effect called modulation discrimination interference (MDI). This paper examines whether MDI is influenced by the similarity in the envelope pattern of the signal and masker. A narrow-band noise (centered at 10 Hz) was used as the signal...

In DSP based IQ modulators generating CPFSK signals, departures from a flat-magnitude, linear phase frequency response in the pass bands of analogue reconstruction filters in the I and Q channels cause ripples in the modulator output signal envelope. These ripples then produce undesirable side-lobes in the output signal spectrum when the signal passes through non-linear elements in the transmis...

This paper presents a highly efficient envelope-tracking (ET) modulator over wide output power range. The ET modulator is designed to operate with a dual-mode power amplifier (PA). The supply voltage of the linear regulator is adjusted according to the average power level for further enhanced efficiency at a low power region. An adaptive bias circuit is designed to avoid the crossover distortio...

Three experiments were designed to provide psychophysical evidence for the existence of envelope information in the temporal fine structure (TFS) of stimuli that were originally amplitude modulated (AM). The original stimuli typically consisted of the sum of a sinusoidally AM tone and two unmodulated tones so that the envelope and TFS could be determined a priori. Experiment 1 showed that norma...

We introduce and experimentally validate a pulse picking technique based on a travelling-wave-type acousto-optic modulator (AOM) having the AOM carrier frequency synchronized to the repetition rate of the original pulse train. As a consequence, the phase noise characteristic of the original pulse train is largely preserved, rendering this technique suitable for applications requiring carrier-en...

The hybrid amplifier that combines a buck converter and linear has been widely used as the envelope tracking (ET) supply modulator for ET power (PA) application. Instead of adding more large off-chip passives to raise efficiency amplifier, this work uses Viterbi-like trellis search (TS) digital signal processing (DSP) algorithm find optimal switching sequence in lowering RMS error current op-am...