Ladder Transformer Coupling Networks for Pulse Amplifiers and Hard-Tube Modulators

This paper discusses the problem of synthesizing a two-port network for coupling a pulse amplifier or a hard-tube modulator to a resistive load which may have an associated shunt capacitance. Coupling networks are limited to those capable of absorbing the lumped-parameter reactance equivalents of the high-frequency distributed parameters of a physical transformer. Thus, an important criterion for network performance is the relative ease with which the equivalent network elements of the transformer may be accommodated. It is shown that one may obtain both decreased rise times and easier transformer accommodation, with step-down networks, by utilizing more complex coupling networks than the usual pulse transformer model. For further improvements, one should consider lowered values of driver impedance. Step-up networks present a more difficult coupling problem, but appreciable enhancement in waveform and some reduction in rise time may again accrue through the incorporation of supplementary network elements.