180Vpp Output Voltage, 24MHz Bandwidth, low power Class AB Current-Feedback High Voltage Amplifier for Ultrasound Transmitters

A novel integrated high-voltage high bandwidth linear amplifier for medical ultrasonic transmitter applications is presented in this brief. Compared to digital high voltage pulsers, linear amplifiers have many advantages, such as lower harmonic distortion and the capability of generating complex arbitrary waveforms for coded-excitation mode. The amplifier employs a current-feedback technique that overcomes the gain bandwidth product limitation of a conventional voltage feedback amplifier, capable of generating a high output signal swing with a wide closed-loop bandwidth. The output stage is a mixed emitter follower and open drain architectures. The amplifier is designed and implemented using a 0.18-mu m CMOS silicon-on-insulator process with 200 V components. When driving a load of 50 pF in parallel with 100 Omega, it's capable of transmitting a sine-wave signal at a frequency of up to 20 MHz, a maximum signal swing of 180 Vpp, a second-order harmonic distortion (HD2) lower than -43 dB and a maximum slew rate of 12 V/ns with only 20 mW average power dissipation with 0.1 % duty cycle.