A feasibility study for arbitrary waveform generation using on-off pulses and modified PWM waveforms in the front-end circuit integrated with transducers

It is a challenge to implement the arbitrary waveform generator (AWG) with high performance devices such as digital to analog converters (DACs) and linear power amplifiers (LPAs) in the front-end circuits which should be integrated with array transducers due to its issue in size and power consumption. Over the past several decades, a number of approaches using only on-off pulses have been proposed to transmit an arbitrary waveform. A pulse width modulation (PWM) technique is one of the approaches to simplify the implementation of AWG into the tramsmitter. In this paper, a preliminary study for an arbitrary waveform generation, which is essential for the coded excitation imaging, using only on-off pulses is introduced. In this study, we propose a proof of concept of an adapted PWM waveform using uni-polar and bi-polar pulses. In theoretical and simulation studies, transmission signals using uni-polar and bi-polar pulses, and the PWM waveforms are analyzed and investigated in terms of a frequency characteristic and a transmission power efficiency (TPE) that indicates the pulse-shaping performance of the generated waveform by defining the ratio of its output and input power through a given transducer. The results demonstrate the possibility to perform the arbitrary waveform generation with the transmitter architecture using only on-off pulses and the PWM waveforms without any DAC and LPA.