Supertex inc.

Supertex inc.

www.supertex.com

MD2134

Doc.# DSFP-MD2134

C102412

DAC

A

B

DGND

AGND

C3A

KA

C1A

C3B C2B

C1B

VREF

+V

REF

M0

M1

M2

M3

EN

SDI

SDO

SCK

CS

LD

VLL

SUB

Data

Latch

&

Control

Logic

Beamform

Switch

Matrix

VDD

+5.0V

+2.5V

PA

XDRC

PB

T1

+3.3V

+3.3V

+70 to 100V

V

PP

GND

KB

C2A

RFB

D2

D1

+5.0V

M1

M2

DN2625

+5.0V

Level

Translator

PAM

Level

Select

DN2625

Block Diagram

High Speed Ultrasound Beamforming Source Driver

Features

delay

P-P

Applications

General Description

The MD2134 is a high-speed source driver for use in a pulsed

current waveform generator. This programmable, fast, arbitrary

current level driver is designed for medical ultrasound imaging

beamforming applications. It also can be used in HIFU, NDT

ultrasound and other instrument applications.

The MD2134 consists of CMOS digital logic input circuits, an

eight-bit current DAC for aperture weighting amplitude control,

and a programmable 15-level pulse amplitude modulation (PAM)

current-source that does not include a zero level. The fast current

sources are constructed with current-switch array, controlled by

the LV0~LV15 level-register as the waveform data points. Four

logic inputs M[3:0] are used for transmit data level selecting, as

well as the transmitting timing control pins. Each level can be

programmed to a resolution of +/-127 including zero (8-bit) in

addition to an 8-bit SPI apodization DAC. The outputs PA and PB

are controlled by M[3:0] pins directly, as well as the polarity-flip bit

S1 in the SPI register. The high-speed SPI interface will achieve

per-scan-line fast data updating for dynamically changing delay

time, weighting and waveforms.

The MD2134 outputs are designed to drive two very low-threshold,

high-voltage depletion N-MOSFETs, such as Supertex’s DN2625s,

as source drivers. The two DN2625 drains are connected to a

center-tap RF pulse transformer. The transformer’s secondary

output connects to a cable and piezoelectric or capacitive

transducer as a load with a good impedance match.