A F-Band ×4 Frequency Multiplier Chip with High Spectral Purity Using Vertically Stacked Marchand Baluns and TF-MSL

A ×4 frequency multiplier chip is presented in this paper. The MMIC was realized in a 35-nm mHEMT technology. It contains a chain of two differential frequency doublers followed by an amplifier. A vertically stacked Marchand balun provides the differential signal for each frequency doubler stage. Due to the use of folded thin film microstrip transmission lines (TF-MSL) and a folded Marchand balun a compact layout was possible. The MMIC achieves a maximum output power of 6.9 dBm and covers almost the whole F-band between 94 GHz and 140 GHz. This is a relative bandwidth of 39.3%. The strongest unwanted harmonic is suppressed by more than 30 dBc starting from 98 GHz. Partly the suppression exceeds 40 dBc.