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This paper presents an efficient envelope amplifier targeted to wideband Envelope Tracking (WBET) and wide-band Envelope Elimination and Restoration (EER). The design combines a Buck DC-DC converter with wideband operational amplifier. The goal is to achieve high operating frequency with good efficiency. The paper revisits some design features like the effect of slew rate limitation of switch current,...
This paper studies the effect of feedback capacitance on the input matching of a class E switching power amplifier. The on/off switching causes the input to see the feedback capacitance either amplified by the Miller effect or not and therefore, this feature is dependent on the gain of the amplifier. The time-varying feedback appears at the gate as negative input resistance, as a cause of severe second...
This work demonstrates a new integrated inverse class E amplifier circuit, employing a pHEMT switching device and fully integrated output network for pulse shaping. The circuit is particularly suitable for full integration, since it does not need any RF choke for biasing, and no DC blocking capacitor is needed between the switch and the output network parallel resonance circuit. The back plate capacitances...
The purpose of this paper is to study the entire dimensioning space of a parallel-tuned integrated circuit that was designed and implemented earlier. The main parameters were swept while keeping the remaining component values fixed, and performance contours were derived. The main finding was that the traditional sweeps of resistively damped switching amplifiers match poorly if the resonator Q value...
This paper discusses the effects of unequal signal delays in the input network of a multi-finger transistor in a switching RF power amplifier. In a design that employs a distributed transistor, the driving signal must be delivered to each transistor finger by conductor segments that usually are unequal in length. The effects of the consequent non-simultaneous switching are demonstrated with three...
This paper demonstrates a tuned power amplifier designed to operate at 1.6 GHz frequency. The basis of the design is inverse class E topology where the DC block is placed in a new position so that the blocking capacitor can be smaller. Further, very high currents flowing into the output resonator had to be taken into account in the design process of a integrated circuit (IC). Wide inductor lines and...
Envelope tracking (ET) technique transmitter employing a linear 0.5 W 1 GHz LDMOS PA (power amplifier) is studied. Four different methods for supply voltage modulation are discussed and measured results are given. Results show improvement both in efficiency and linearity when predistortion of the supply voltage is added. The same linear amplifier was used also in an envelope elimination and restoration...
The purpose of this work is to study feedthrough cancellation methods available for a class E amplified polar transmitter. A mathematical feedthrough cancellation using measured S-parameters is presented. The results show a clear improvement to the nonlinear behaviour of a class E amplifier. Also, a transistor level possibility of feedthrough cancellation is discussed and simulated. With a large-signal...
An efficiency enhanced power amplifier is presented. The amplifier uses envelope tracking (ET) technique and static predistortion to achieve high linearity. The effects of drain voltage modulation to experimental amplifier's gain, phase as well as bandwidth are measured using simple single-tone tests and discussed. Then the amplifier's ET performance is evaluated. The complete envelope tracking system...
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