A YIG-tuned nonlinear transmission line multiplier

A distributed frequency multiplier with a yttrium-iron-garnet (YIG)-tuned output filter for stable, yet infinitely tunable microwave signals is described. The multiplier is a nonlinear transmission line (NLTL) which can be driven with a 10-200 MHz, 1-3 W sinusoidal power source to produce a voltage sawtooth wave with greater than 200 harmonics. These harmonics are selected by a YIG-tuned bandpass filter, resulting in sinusoidal outputs with low spurious content and a frequency stability derived from the source. This circuit offers tunability far exceeding that of step-recovery diode multipliers at the expense of increased size and lower efficiency. An important result of the present experiment is that practical monolithic multipliers for millimeter-wave outputs can be filtered with little or no degradation in their performance.<>