A High-Voltage DAC-Based Transmitter for Coded Signals in High Frequency Ultrasound Imaging Applications

An ultrasound transmitter based on a high-voltage digital-to-analog converter (HVDAC) is presented in this paper. The transmitter is implemented in a 0.25-
$\mu \text{m}$
high-voltage CMOS process provided by foundry, integrating the digital control circuitry and HVDAC on a single chip. By employing a fast-slewing DAC in conjunction with a standard DAC, the proposed circuit is optimized for high-speed operations even for a load with large capacitance, making it well suited for applications where piezoelectric transducers are utilized. With an output loading of 180 pF //
$50~\Omega $
, the HVDAC operates at a sampling rate of 150 MS/s, while providing a maximum output swing of 31.5
$\text{V}_{\mathrm {PP}}$
. The spurious-free dynamic range is 46 dB at 1-MHz output frequency and 31 dB at Nyquist frequency, which is analyzed in detailed and proved in good agreement with the measurement results. Tested with a chirp signal sweeping from 15.75 to 34.25 MHz in 2-
$\mu \text{s}$
and a transducer model centered at 25 MHz with a 13.75-MHz bandwidth, the compressed pulse after matched filtering shows a −6-dB pulse width of 153 ns with a peak sidelobe of −40 dB, which successfully demonstrates the capability for coded signals excitation at high frequency.