A Frequency Multiplier-by-8 Chip Into G-Band with High Spectral Purity Using Space-Efficient Transformer-Based Baluns and TF-MSL

This paper presents an X8 frequency multiplier chip, realized in a 35 nm mHEMT technology. Its topology is a differential quadrupler followed by a differential doubler with a buffer amplifier next to each multiplier. The differential signal is provided by space-efficient transformer-based baluns. Together with the use of folded thin-film microstrip transmission lines (TF-MSL) a very compact layout has been realized. The circuit reaches a maximum output power of 6.2 dBm. The 15.2% wide 3-dB-bandwidth ranges from 146 to 170 GHz. In the operational frequency band between 150 and 170 GHz the strongest unwanted harmonic is suppressed by more than 35 dBc and achieves 50.7 dBc on average.