An apparatus and method to produce a waveform. The apparatus includes a first node, a first power supply coupled to a second node, a first switch that couples the second node to the first node, and responsive to the first switch being closed, a peak voltage is applied at the first node. The apparatus also includes a second switch that couples a third node to the first node, and responsive to the second switch being closed, a voltage step is applied at the first node. In addition, a second power supply is coupled to the first node to produce a ramped voltage at the first node.