Datasheet

30129710
FIGURE 6. Beamformer Output Example
PULSE WIDTH ADJUST
30129706
FIGURE 7. High-Voltage Pulser
Figure 7 is a diagram for a high-voltage pulser such as the
LM96550. The input control signals Pn/Nn are provided by the
beamformer output. These signals are level shifted up/down
to the high voltage “HV”/”-HV” and buffered to drive the output
stage of M1/M2 to generate high-voltage outputs. High lin-
earity and low distortion are typically required for pulser out-
puts. To achieve this, the duty cycles of output pulses should
be as close to 50% as possible. Due to the non-ideal nature
and differences between the two signal paths, from Pn to g1,
and from Nn to g2, it is very difficult achieve an ideal 50% duty
cycle at the pulser outputs, even if the Pn and Nn inputs are
perfectly at equal pulse width.
To address this challenge, the LM96570 can tune the pulse
width of its outputs Pn/Nn to compensate the path difference,
as shown in Figure 8. In the ideal case, the pulse width of Pn
and Nn is equal, tp1’=tp2’, and the corresponding pulser out-
put duty cycle is 50%, tp1=tp2. However, in the typical case,
tp1 is not equal to tp2; instead, for example, tp1>tp2. The
LM96570 can then change the pulse width of Pn and Nn so
that tp1'<tp2' to compensate for the difference, thus making
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LM96570