High-efficiency Ka band microwave monolithic integrated circuit frequency tripler using lumped-element balun

This work describes a lumped-element balun for use in a miniature, coplanar waveguide frequency tripler pseudomorphic high electron mobility transistor microwave monolithic integrated circuit. The measurement results of the balun show a 1-dB gain balance and a 10 degrees phase balance from 11.6 to 13 GHz. It was used in the design of a 36-GHz monolithic tripler at the input port. A resonant inductor and capacitor (LC) filter was used to eliminate the fundamental frequency and a phase delay line was employed to enhance the third harmonic in the tripler. At 36 GHz, the tripler achieved as minimum conversion loss of 6.7 dB at an input power of 13 dBm; the suppressions of the fundamental and second harmonic frequencies were 24 and 27 dB, respectively.