An ultra-wideband MMIC balanced frequency doubler using line-unified HEMTs

A very small, ultrawideband, MMIC balanced frequency doubler that uses line-unified HEMT configurations is proposed. A chip size of 1.0 mm×0.9 mm is achieved with a conversion loss of 8-10 dB in the 4-40-GHz output harmonics frequency range and fundamental frequency signal isolation of better than 21 dB above the input fundamental frequency of 7 GHz. Circuit parameters are optimized in a novel and simple prediction using an equation derived from the HEMT´s DC characteristic and a linear-state CAD software package. The doubler has promise for realizing miniaturized, wideband MMIC transmitters/receivers