ALLPCB
Background
The global population is increasing and aging, driving demand for compact, energy-efficient, and cost-effective medical diagnostic and care devices. Portable diagnostic systems, especially portable ultrasound, are increasingly needed for use in clinics, ambulances, emergency responders, disaster zones, battlefields, and other remote areas with limited medical services.
Traditional B-mode and color Doppler ultrasound systems are typically large, bench-top devices. Designing a portable ultrasound system requires addressing power and performance constraints: battery-powered devices must minimize energy consumption while ensuring sufficient battery life during operation, and small form factors must still deliver high image resolution to support clinical decision-making.
PowerWise 8-Channel Chipset Overview
US semiconductor company National Semiconductor recently introduced an 8-channel ultrasound transmit/receive chipset called PowerWise. The chipset uses a circuit architecture intended to enable longer battery life and image resolution approaching that of larger ultrasound scanners in portable designs.
Figure: PowerWise 8-channel ultrasound transmit/receive chipset
Chipset Components and Capabilities
The 8-channel solution comprises four chips that integrate the necessary circuitry: an analog front end (AFE) LM96511 for the receive path, a transmit/receive switch LM96530, a pulser LM96550 for the transmit path, and a configurable transmit beamformer LM96570. The integration enables designers to build compact 128-channel portable ultrasound systems by combining multiple chipset instances.
The four chips cooperate to improve overall performance and efficiency. For example, reconfiguring the transmit beamformer can calibrate delay errors from PCB routing and pulser timing, reducing distortion and enabling second-harmonic imaging. The transmit/receive switch provides flexibility in bias-current settings so designers can trade off power consumption and performance.
Analog Front End
The analog front end uses a distinctive architecture aimed at delivering high image quality while minimizing B-mode power consumption. It integrates a high-resolution digital variable gain amplifier (DVGA) and a low-power continuous-time sigma-delta (CTSD) analog-to-digital converter (ADC). The DVGA offers calibration advantages across channels and improved signal spectrum performance compared with traditional analog VGAs. The CTSD ADC provides strong brick-wall alias rejection; compared with conventional pipelined ADCs, the CTSD approach reduces power and improves alias filtering.
System Integration and Support
The vendor supplies signal-path components such as clock circuitry and power-management chips to support portable ultrasound system designs. Evaluation kits, reference schematics, and design tools are provided to aid design evaluation and system integration.
