The AD8339 is a quad programmable I&Q demodulator with phase shifter that is ideally suited for medical ultrasound systems. In ultrasonic beam-forming applications like continuous wave (CW) Doppler ultrasound, the AD8339 reduces board space by as much as 75 percent compared to competing devices by replacing the large crosspoint-switch matrices and analog delay lines typically used in phased-array beam forming. The AD8339 consumes just 73mW/channel, which is 30 percent less than competitive solutions, allowing medical instrument manufacturers to provide CW Doppler capabilities in portable and battery-powered equipment. Alternately, the power savings of the new device enables designers to increase the channel density of cart-based ultrasound systems, which often use hundreds of phase shifters per unit.

The AD8339 features a simple three-wire SPI (serial peripheral interface) interface for digital control of channel selection and phase states by system computer commands. A single synchronized common LO (local oscillator) input for all channels enables precise phase locking to the system clock. The new device features a quadrature phase error of ±0.5°, and I&Q amplitude imbalance of 0.25 dB. The LO frequency range is 100 MHz and the basic RF input frequency range is 25 MHz.

The new phase shifter works well with Analog Devices' AD8332, AD8334 and AD8335 VGAs, the AD8021 high-speed voltage-feedback amplifier, the AD7686 and AD7693 PulSAR® analog-to-digital converters and the AD9510 clock distribution IC.

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