New Technique to Cancel IMD3 in Electroacoustic Filters

This work presents a new technique to cancel third-order intermodulation distortion (IMD3) by using a low frequency injected tone to generate a second-order intermodulation product (IMD2) that fall exactly at the same frequency of the undesired IMD3. The phase and amplitude of the injected tone are controlled to cancel out the IMD3. A proper characterization and a good modeling are needed to demonstrate the concept. Narrow band characterization and modeling of second harmonic (H2) and IMD3 in a Bulk Acoustic Wave (BAW) resonator has been done to evaluate the nonlinear contribution of each material composing the resonator and to identify the dominant nonlinear terms. The concept of this technique will be demonstrated by doing measurements of an on-wafer resonator. The measurement system, including the cancellation procedure, will be described. The cancellation achieved with this technique is in good agreement with the simulations.