VHDL-AMS behavioural modelling of a CMUT element

This paper reports the development, implementation and simulation of a behavioural model written in VHDL-AMS for a capacitive micromachined ultrasonic transducer (CMUT). Unlike previous behavioural models, this model incorporates the non-linear electro-mechanical relation of the CMUT. VHDL-AMS was chosen for the ease with which it can be used to implement these relations, and for its portability between software platforms. To the best of the authors´ knowledge, this is the first reported VHDL-AMS model of a CMUT. The simulation results demonstrate that the model can be used to sumulate a number of scenarios, including frequency responses, time responses and effects of DC bias voltage. Results are compared to a finite element method model, and show excellent agreement in resonant frequency and a 16% error in pull-in voltage.