A focused ultrasound system comprises a transducer having a multiplicity of transducer elements, drive circuitry that generates and outputs a plurality of drive signals, each offset by a respective phase difference, and a controller for selectively coupling the drive signals to respective transducer elements, the controller including a plurality of first tier switching modules and second tier switching modules. Each first tier module receives as an input the plurality of drive signals and outputs one of the drive signals in response to a drive signal selection signal. Each second tier module is coupled to a respective grouping of transducer elements and selectively couples a respective selected drive signal output from a first tier switching module to one or more of the transducer elements in response to a transducer element selection signal.
