Friday, June 29, 2007

The AD9271—A Revolutionary Solution for Portable Ultrasound

Medical ultrasound systems, among the more complex signal processing devices in use today, are used for real-time detection of health problems and general diagnostic procedures. Slower than radar and faster than sonar, ultrasound systems have become increasingly portable, evolving from cart-based systems into palm-sized devices. This article discusses some of the necessary ingredients of compactness.



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Tuesday, June 05, 2007

High-Speed DAC Controls Power Amplifier Ramp Profile

A high-speed current-output DAC and a single op amp can generate a power amplifier (PA) ramp profile that fits the RF gain requirements for TDMA. The ramp is applied to the voltage control pin of a variable-gain amplifier (VGA) to control the gain of the RF signal entering the PA.

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Reducing Ground Bounce in DC-to-DC Converters—Some Grounding Essentials

Electrical ground looks simple on a schematic, but circuit performance is dictated by the PCB layout. Ground-node analysis is difficult, especially for dc-to-dc converters, such as buck and boost circuits, which pound the ground node with large, fast-changing currents. When ground moves, performance suffers and the system radiates EMI. An understanding of ground noise can provide a sense for reducing the problem.

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