1. An ultrasound imaging system, comprising: a broadband ultrasound transducer configured to transmit ultrasound pulses towards a target; and a processing subsystem operatively coupled to the broadband ultrasound transducer and configured to: convolve one or more base ultrasound pulses corresponding to a particular frequency with a desired code to generate an extended excitation wave; transmit the extended excitation wave to the broadband ultrasound transducer to be transmitted towards the target; receive echo signals reflected back from the target in response to the extended excitation wave; de-convolve the received echo signals; and generate one or more ultrasound images of the target corresponding to multiple frequencies based on the de-convolved echo signals.