MEASURE BIPOLAR SQUARE WAVE SIGNALS GENERATOR

PA imaging offers unique capabilities in studying biological tissue based on optical absorption contrast. Currently, besides conventional B-mode and Doppler ultrasonic modality, advanced imaging formation method, such as photo-acoustic (PA) imaging, elasto-graphic imaging, as well as harmonic imaging is gradually becoming an important medical assessment tool for these echo-graphic systems.

MEASURE BIPOLAR SQUARE WAVE SIGNALS GENERATOR

The overall quiescent current is 2 A and the second harmonic distortion is as low as Р Р†РІвЂљВ¬РІР‚в„ў40 dBc, indicating that the integrated pulse generator can be used in advanced, portable ultrasonic harmonic imaging systems.Р вЂќР’В¬ompared with computed tomography (CT), X-ray and magnetic resonance imaging (MRI), medical ultrasound imaging is relatively fast, inexpensive, portable and radiation-free, and has become one of the most popular modalities in clinical examination. The rise and fall times of the pulses are within 18.6 and 18.5 ns, respectively.

The entire circuit integrates an 8-channel pulse generator, producing pulse signals >100 Vpp. Based on these considerations, the pulse generator architecture with balanced rising and falling edges proposed in this chapter is designed by synthesizing low-power, high-speed level shifters and a high-voltage H-bridge output stage to output high-voltage pulse signals with low harmonic distortion. In addition, the second harmonic leakage of the high-voltage pulse signal output by the pulse generator needs to be controlled such that the pulse generator can be applied to tissue harmonic imaging. Since ultrasonic transducers are usually composed of piezoelectric materials, most of which are capacitive, and the resonant frequency is usually in the order of tens of MHz, it is preferred to convert the high-frequency excited signals into high-voltage pulses to efficiently drive the transducers. This chapter describes the use of silicon-on-insulator (SOI) technology to develop balanced slew-rate pulse generators for medical ultrasound scanners, especially for multi-channel portable systems.

Measure bipolar square wave signals