In-Line Signal Circuit for Broad-Band Parametric Amplifiers

A new double-tuned parametric amplifier signal-circuit configuration and a method for its experimental optimization is described. A new in-line signal circuit, which is adapted from a quarter-wave-coupled bandpass filter, is intended for use at higher microwave and millimeter-wave parametric amplifiers (paramps). It is shown that, using this signal circuit, a broader flat-gain response can be obtained as compared with the conventional double-tuned signal circuit with broad-banding stub placed multihalf-wavelength apart from the diode. To suppress the spurious response, a semilumped approximation is applied in the design. Finally, a "cold and hot" test method to optimize the double-tuned signal circuit is introduced.