DC to 50 MHz, Dual I/Q Demodulator and
Dual integrated I/Q demodulator
16 phase select options on each output (22.5° per step)
Quadrature demodulation accuracy
Phase accuracy: ±0.1°
Amplitude balance: ±0.05 dB
4 × LO: 10 kHz to 200 MHz
RF: dc to 50 MHz
Baseband: determined by external filtering
Output dynamic range: 159 dB/Hz
LO drive > 0 dBm (50 Ω); 4 × LO > 1 MHz
Supply: ±5 V
Power consumption: 190 mW/channel (380 mW total)
Medical imaging (CW ultrasound beamforming)
Phased array systems (radar and adaptive antennas)
The AD83331 is a dual phase-shifter and I/Q demodulator that
enables coherent summing and phase alignment of multiple
analog data channels. It is the first solid-state device suitable for
beamformer circuits, such as those used in high performance
medical ultrasound equipment featuring CW Doppler. The RF
inputs interface directly with the outputs of the dual-channel,
low noise preamplifiers included in the AD8332.
A divide-by-4 circuit generates the internal 0° and 90° phases
of the local oscillator (LO) that drive the mixers of a pair of
matched I/Q demodulators.
The AD8333 can be applied as a major element in analog
beamformer circuits in medical ultrasound equipment.
The AD8333 features an asynchronous reset pin. When used
in arrays, the reset pin sets all the LO dividers in the same state.
Sixteen discrete phase rotations in 22.5° increments can be selected
independently for each channel. For example, if Channel 1 is used
as a reference and the RF signal applied to Channel 2 has an I/Q
phase lead of 45°, Channel 2 can be phase aligned with Channel 1
by choosing the correct code.
1 Protected by US Patent 7,760,833.
FUNCTIONAL BLOCK DIAGRAM
CH 1 ΦSEL
CH 2 ΦSEL
Phase shift is defined by the output of one channel relative to
another. For example, if the code of Channel 1 is adjusted to
0000 and that of Channel 2 is adjusted to 0001 and the same
signal is applied to both RF inputs, the output of Channel 2
leads that of Channel 1 by 22.5°.
The I and Q outputs are provided as currents to facilitate sum-
mation. The summed current outputs are converted to voltages
by a high dynamic range, current-to-voltage (I-V) converter, such
as the AD8021, configured as a transimpedance amplifier. The
resultant signal is then applied to a high resolution ADC, such as
the AD7665 (16 bit/570 kSPS).
The two I/Q demodulators can be used independently in other
nonbeamforming applications. In that case, a transimpedance
amplifier is needed for each of the I and Q outputs, four in total
for the dual I/Q demodulator.
The dynamic range is 159 dB/Hz at the I and Q outputs, but the
following transimpedance amplifier is an important element in
maintaining the overall dynamic range, and attention needs to
be paid to optimal component selection and design.
The AD8333 is available in a 32-lead LFCSP (5 mm × 5 mm)
package for the industrial temperature range of −40°C to +85°C.
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibilityisassumedbyAnalogDevices for itsuse,nor foranyinfringementsofpatentsor other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2005–2016 Analog Devices, Inc. All rights reserved.