Linear power amplifier for high frequency ultrasound coded excitationimaging

Commercial function generators and power amplifiers are generally used inhigh frequency coded excitation imaging systems. In order to minimize size,reduce external noise and deliver transmit energy to transducer efficiently in asystem with the coded excitation, digital waveform generator and poweramplifier should be placed on a single board. The pulser with capability ofdoing arbitrary waveform amplification was custom-designed and developed for ahigh frequency coded excitation imaging system. The matching of input stage wasachieved by transmission line transformer (TLT) with ferrite core. Using TLT,matching circuit became simple otherwise it would require matching circuit usinglumped components. Transformers were used between stages. The 6dB bandwidth ofdeveloped amplifier was from 10MHz to 110MHz. In the pass band, the gain ofamplifier fluctuated within 4dB. Wire target measurements and ex-vivomeasurements on tissues clearly demonstrated its superior performance.