AD8333是一款双通道移相器和
I/Q demodulator，可实现多个模拟数据通道的相干求和与相位对准。它是首款适合波束生成器电路的固态器件，此类电路可用于具有连续波多普勒模式的高性能医疗超声设备中。RF输入直接与
AD8332内置的双通道、低噪声前置放大器输出进行接口。
A four-way circuit generates the internal 0° and 90° phases of the local oscillator (LO) to drive a pair of mixers matched to the I/Q demodulator.
The AD8333 can be used as the primary component of analog beamforming circuitry in medical ultrasound equipment.
The AD8333 has an asynchronous reset pin. When used as an array, this reset pin sets all LO dividers to the same state. Each channel can be independently selected for 16 discrete phase rotations in 22.5° increments. For example, if channel 1 is used as a reference channel and the I/Q phase of the RF signal applied to channel 2 is 45° ahead, channel 2 and channel 1 can be phase-aligned by selecting the correct code.
Phase shift is determined by the output of one channel relative to another. For example, if the code for channel 1 is adjusted to 0000 and channel 2 is adjusted to 0001, and the same signal is applied to the RF inputs of both channels, the output of channel 2 will be 22.5° ahead of the output of channel 1.
Both the I and Q outputs are provided in current for easy summing. The summed current output is converted into voltage by configured as a high dynamic range, current-voltage (I-V) converter configured as a transconductance amplifier, such as the AD8021. The resulting signal is then applied to a high-resolution ADC, such as the AD7665 (16bits/570 kSPS).
In other non-beamforming applications, the two I/Q demodulators can be used independently. At this point, a transconducting amplifier is required for each I and Q output, for a total of four transconducting amplifiers for dual I/Q demodulators.
The dynamic range is 159 dB/Hz for each I and Q output, but to maintain the entire dynamic range, the rear transconducting amplifier is important, and care should be taken to optimize device selection and design.
The AD8333 is available in a 32-pin LFCSP (5 mm x 5 mm) package and is rated for an industrial temperature range of −40°C to +85°C.
Protected by U.S. Patent No. 7,760,833.
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医疗成像（连续波超声波束成形）
相控阵系统（雷达和自适应天线）
通信接收机