Amplifier

About: Amplifier is a research topic. Over the lifetime, 163941 publications have been published within this topic receiving 1361964 citations. The topic is also known as: amp & amplifier.

Idealized operation of the class E tuned power amplifier

Abstract: The class E tuned power amplifier consists of a load network and a single transistor that is operated as a switch at the carrier frequency of the output signal. The most simple type of load network consists of a capacitor shunting the transistor and a series-tuned output circuit, which may have a residual reactance. Circuit operation is determined by the transistor when it is on, and by the transient response of the load network when the transistor is off. The basic equations governing amplifier operation are derived using Fourier series techniques and a high- Q assumption. These equations are then used to determine component values for optimum operation at an efficiency of 100 percent. Other combinations of component values and duty cycles which result in 100-percent efficiency are also determined. The harmonic structure of the collector voltage waveform is analyzed and related amplifier configurations are discussed. While this analysis is directed toward the design of high-efficiency power amplifiers, it also provides insight into the operation of modern solid-state VHF-UHF tuned power amplifiers.

Digital predistortion of wideband signals based on power amplifier model with memory

Abstract: Memory effects in the power amplifier limit the performance of digital predistortion for wideband signals. Novel algorithms that take into account such effects are proposed. Measured results are presented for single and multicarrier UMTS signals to demonstrate the effectiveness of the new approach.

A New High Efficiency Power Amplifier for Modulated Waves

Abstract: This paper introduces a new form of linear power amplifier for modulated radio-frequency waves. Plate circuit efficiencies of sixty to sixty-five per cent independent of modulation are obtained by means of the combined action of varying load distribution among the tubes and varying circuit impedance over the modulation cycle. The theory of operation is developed and detailed observations on the behavior of tubes in the new circuit are given in the paper. The use of stabilized feedback in connection with this circuit is discussed and significant measurements on a laboratory model of a fifty-kilowatt transmitter are shown.

Power Waves and the Scattering Matrix

Abstract: This paper discusses the physical meaning and prop-erties of the waves defined by [Equation], [Equation] where V/sub i/, and Z/sub i/, are the voltage at and the current flowing into the ith port of a junction and Z/sub i/, is the impedance of the circuit connected to the ith port. The square of the magnitude of these waves is directly related to the exchangeable power of a source and the reflected power. For this reason, in this paper, they are called the power waves. For certain applications where the power relations are of main concern, the power waves are more suitable quantities than the conventional traveling waves. The lossless and reciprocal conditions as well as the frequency characteristics of the scattering matrix are presented. Then, the formula is given for a new scattering matrix when the Z/sub i/'s are changed. As an application, the condition under which an amplifier can be matched simultaneously at both input and output ports as well as the condition for the network to be unconditionally stable are given in terms of the scattering matrix components. Also a brief comparison is made between the traveling waves and the power waves.

CMOS analog integrated circuits based on weak inversion operations

Abstract: A simple model describing the DC behavior of MOS transistors operating in weak inversion is derived on the basis of previous publications. This model includes only two parameters and is suitable for circuit design. It is verified experimentally for both p- and n-channel test transistors of a Si-gate low-voltage CMOS technology. Various circuit configurations taking advantage of weak inversion operation are described and analyzed: two different current references based on known bipolar circuits, an amplitude detector scheme which is then applied to a quartz oscillator with the result of a very low-power consumption (<0.1 /spl mu/W at 32 kHz), and a low-frequency bandpass amplifier. All these circuits are insensitive to threshold and mobility variations, and compatible with a CMOS technology dedicated to digital low-power circuits.