The dual-fed distributed amplifier

A conventional microwave distributed amplifier consists essentially of a gate artificial transmission line and a drain artificial transmission line which have common active components in the form of MESFETs that provide the gate-and-drain-line shunt capacitances. Such amplifiers have an input port to the gate line and an output port from the drain line. The unused gate and drain ports are terminated in the appropriate characteristic impedances. A method is presented or a dual-fed distributed amplifier, using a small number of MESFETs, in which the gain is significantly increased and the noise figure significantly reduced by feeding the signal power into both gate-line ports. Provided the amplifier operates under small-signal (linear) conditions, superposition will apply to its operation, and the output due to two forward gain signals will add to produce the total output power. This arrangement increases available gain from the amplifier in comparison with its conventional mode of operation and a concommitant reduction in noise figure. Examples verifying the design are discussed.<>