FET amplifier

About: FET amplifier is a research topic. Over the lifetime, 7048 publications have been published within this topic receiving 77549 citations.

The design of tetrode transistor amplifiers

Abstract: The design of tetrode transistor amplifiers encounters problems of the type that occurs with other transistor uses. Desired frequency characteristics, limitations of parasitic elements, and other practical considerations impose constraints on the range of terminations that can be employed. With many transistors, one can terminate a transistor so that it will oscillate without external feedback; this oscillation or other exceedingly sensitive terminations must be avoided. The two-port parameters of the transistor in any orientation in which it is to be used constitute the fixed or given information which is the starting point of the amplifier design. Using this starting point, methods are developed by which one can select, on simple bases, the kinds of terminations that will be suitable. To facilitate the design of amplifiers, a set of charts has been developed from which one can read power gain and input impedance as functions of the load termination. Illustrative tetrode amplifiers are described. These include a common base 20-mc video amplifier, a common-emitter 10-mc video amplifier, an IF amplifier centered at 30 mc, and an IF amplifier centered at 70 mc. Predicted and measured gains are compared.

Reconfigurable tunable RF power amplifier

Abstract: A multi-band, multi-standard programmable power amplifier having tunable impedance matching input and output networks and programmable device characteristics. The impedance of either or both of the impedance matching input and output networks is tunable responsive to one or more control signals. In one example, the programmable power amplifier incorporates a feedback control loop and the control signal(s) are varied responsive to the feedback loop.

A wideband GaN Doherty amplifier with 35 % fractional bandwidth

Abstract: A wideband Doherty amplifier designed and implemented in GaN HEMT technology using simple circuitry is reported. The usefulness of the conventional quarter-wave impedance transformer at the output of the main amplifier for achieving wideband Doherty performance up to 35 % fractional bandwidth is experimentally verified. This simplifies the bandwidth limitation problem of the Doherty amplifier into the wideband design of the main amplifier, peaking amplifier and the input power divider. Based on this, a wideband Doherty amplifier was designed to cover a bandwidth of 640 MHz, ranging from 1.5 GHz to 2.14 GHz. For instance, the designed Doherty amplifier achieved a 1 dB compression output power of P 1dB = 43.8 dBm (24.1 W), with a maximum power-added efficiency of PAE = 69 % (drain efficiency of η = 76 %) at 1.9 GHz. At 6 dB output back-off from P 1dB , a PAE of 45 % (η = 47 %) was measured. The designed Doherty amplifier also showed acceptable linearity when characterized with two-tone and single-carrier wideband code-division multiple access (W-CDMA) stimuli. To the best of authors' knowledge, this work introduces the most wideband Doherty amplifier published so far.

Amplifier mode switch

Abstract: A power amplifier includes a main amplifier having a first output. An auxiliary amplifier has a second output coupled to the first output. A splitter splits a RF input into a first input provided to the main amplifier and a second input delayed by one/quarter wavelength provided to the auxiliary amplifier. A bias control is coupled to the auxiliary amplifier for controllably switching operation of the power amplifier between two different modes of operation.