The MD2133 from Supertex is a high-speed source-driver for pulsed current applications. The MD2133 is programmable, and is targeted for medical ultrasound beam-forming applications. It can also be used in High Intensity Focused Ultrasound (HIFU), Non-Destructive Testing (NDT) using ultrasound, Laser Diode Drive, and other instrumentation applications such as arbitrary waveform generation.
The MD2133 contains CMOS digital logic input circuits, an 8-bit current DAC for aperture weighting control, as well as an 8-bit fast pulse current switch matrix. The MD2133 supports both Pulse-Current Amplitude Modulation (PAM) and Pulse-Width Modulation (PWM) with an in-phase and quadrature I-Q current-switch, and a built-in sine and cosine angle-to-vector look-up table. The angular resolution of the vector table is 1.4°/step with a total range of 256 steps/360°. The 8x1k bits waveform memory can pre-store data for up to four waveforms. The stored parameters for each include data length, start address, cycle limits or continuous looping mode, the transmit frequency pre-scale (N divisor), selection for polarity swapping (fast launch), chirp-up /down for FM and forward / reverse transmit (time-symmetrical waveforms for fewer data points). Two SSTL differential clock inputs control all the waveform writing, read back, transmit delay, and frequencies. The high-speed SPI bus enables fast data updates per-scan-line updating for dynamically changing delay times, as well as for weighting and waveform selection.