An array of CMUT cells has a DC bias voltage (VB) coupled to the membrane and floor electrodes of the cells to bias the electrode to a desired collapsed or partially collapsed state. The low voltage or ground terminal of the DC bias supply is coupled to the patient-facing membrane electrodes and the high voltage is applied to the floor electrodes. An ASIC for controlling the CMUT array is located in the probe with the array. The ASIC electronics are electrically floating relative to ground potential of the ultrasound system to which the CMUT probe is connected. Control and signal lines are coupled to the CMUT probe by level shifters which translate signals to the floating potential of the ASIC and provide DC isolation between the CMUT probe and the ultrasound system.