condition such a channel down condition occurs for example if the channel driving line becomes disconnected from its associated transducer element 20 or if the transducer element 20 is damaged the reference voltage dac 68 and its associated latch not shown are used to set the reference voltage for all the waveform dacs 66 this allows the total power level of the ultrasound source 14 to be adjusted in real time during sonication without requiring reloading of the digital waveform memories 66 the analog circuit 52 comprises forty eight 48 amplication circuits only one of which is shown each of which receives the analog signal output of an associated waveform dac 66 and outputs a corresponding analog radio frequency rf signal that is applied to the channel driving line extending to an associated transducer element 20 the advantages of having each transducer element 20 connected to its own driving line include the reduction of the driving system size cost and power loss when the energy is transmitted from the driving electronics to the transducer element array one of the amplification circuits is better illustrated in fig6 and comprises a first op amp stage 80 that provides a voltage gain to the analog signal and a second op amp stage 82 that provides a high current analog signal output in this embodiment the first op amp stage 80 applies a voltage gain of eleven 11 to the dac analog output signal augmenting the voltage swing from 0 to 11 volts the op amp stage 80 cuts out high frequencies and can be used to cut the quantization noise frequency the signal output by the op amp stage 80 is high pass filtered.