ORIGIN AND
EFFECTS OF INTERMODULATION IN RF MEMS CAPACITORS
D. GIRBAU, N. OTEGI, A. LĂZARO, L. PRADELL
Abstract. This work presents a study of intermodulation distortion in RF
MEMS capacitors. The generation of 3rd and 5th order distortion and its
origin in the displacement of the mobile membrane, are demonstrated. A
numerical non-linear model for simulating intermodulation is presented and
validated by means of measurements for the general 2-tone case. It is
shown that, along with intermodulation, the two RF tones at a MEMS
capacitor also generate a time-varying capacity. Generation of
intermodulation in MEMS driven by digitally-modulated communication
signals is also demonstrated, and its main effects are characterized. A
measurement set-up to measure IMD for 2-tone test as well as for digital
modulations is proposed. |