Characterisation of a transformer balun for a 7–15 GHz SiGe frequency doubler

摘要

A compact transformer balun with less than 0.13 dB magnitude imbalance and 0.4° phase imbalance from 7 to 15 GHz is presented. The balun is suitable for use with frequency doublers using a balanced circuit architecture. Measured data for the balun is used to predict the harmonic rejection of the frequency doubler. The fundamental rejection is 29 dB and third harmonic rejection is better than 35 dB. The balun is 420 μm by 320 μm.