Highly miniaturized LO leakage rejection filters employing spiral lines for application to Ku-band commercial wireless communication system

In this work, spiral inductor structures employing SiN film were fabricated on GaAs substrate for a suppression of LO and its second harmonic leakage signals. Concretely, they were properly designed so that the self-resonance frequency was accurately tuned to LO and its second harmonic frequency, and they were integrated on the downconverter MMIC. Owing to the optimally designed on-chip spiral inductor filters, the downconverter MMIC showed a highly suppressed LO leakage power of -35 dBm and second harmonic LO leakage power of -53 dBm without external filters.