Modified operational transconductance amplifier macromodel application in piezoelectric active filter design

A modified macromodel of operational transconductance amplifier is proposed for application in design of high-frequency bandpass active filters based on film bulk acoustic resonators. The presented solution is an optimal tradeoff according to the criteria of completeness of simulated characteristics, its accuracy and calculation time. Nonlinear amplification behavior of the macromodel is modelled by minimax Chebyshev approximation which allows the use of highorder polynomials and solves the convergence challenge. At the same time, bias-dependent noise model accounts for Johnson-Nyquist and flicker noise sources enabling the evaluation of active filter´s signal-to-noise ratio, noise figure and output dynamic range. Finally, the differential active filter circuit was analyzed to validate the macromodel´s capabilities, simulation ranges and filter characteristics.