250 kSPS, 12-Bit Impedance Converter,
Network Analyzer
AD5934
Rev. A
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FEATURES
Programmable output peak-to-peak excitation voltage
to a maximum frequency of 100 kHz
Programmable frequency sweep capability with
serial I
2
C interface
Frequency resolution of 27 bits (<0.1 Hz)
Impedance measurement range from 1 kΩ to 10 MΩ
Capable of measuring 100 Ω to 1 kΩ with additional circuitry
Phase measurement capability
System accuracy of 0.5%
2.7 V to 5.5 V power supply operation
Temperature range: −40°C to +125°C
16-lead SSOP package
APPLICATIONS
Electrochemical analysis
Bioelectrical impedance analysis
Impedance spectroscopy
Complex impedance measurement
Corrosion monitoring and protection equipment
Biomedical and automotive sensors
Proximity sensing
Nondestructive testing
Material property analysis
Fuel/battery cell condition monitoring
GENERAL DESCRIPTION
The AD5934 is a high precision impedance converter system
solution that combines an on-board frequency generator with a
12-bit, 250 kSPS, analog-to-digital converter (ADC). The
frequency generator allows an external complex impedance to
be excited with a known frequency. The response signal from
the impedance is sampled by the on-board ADC and a discrete
Fourier transform (DFT) is processed by an on-board DSP
engine. The DFT algorithm returns a real (R) and imaginary (I)
data-word at each output frequency.
Once calibrated, the magnitude of the impedance and relative
phase of the impedance at each frequency point along the sweep
is easily calculated using the following two equations:
Magnitude
=
2
2
I
R
+
Phase
= tan
−1
(
I
/
R
)
A similar device, available from Analog Devices, Inc., is the
, which is a 2.7 V to 5.5 V, 1 MSPS, 12-bit impedance
converter, with an internal temperature sensor, available in a
16-lead SSOP.
FUNCTIONAL BLOCK DIAGRAM
ADC
(12 BITS)
VDD/2
DDS
CORE
(27 BITS)
DAC
V
BIAS
Z(
ω
)
I
2
C
INTERFACE
IMAGINARY
REGISTER
GAIN
REAL
REGISTER
1024-POINT DFT
LPF
SCL
SDA
DVDD
AVDD
MCLK
AGND
DGND
R
OUT
VOUT
AD5934
RFB
VIN
05
32
5-
0
01
Figure 1.
Summary of Contents for AD5934
Page 35: ...AD5934 Rev A Page 35 of 40 SCHEMATICS 05325 144 Figure 40 EVAL AD5934EBZ USB Schematic ...
Page 36: ...AD5934 Rev A Page 36 of 40 05325 145 Figure 41 EVAL AD5934EBZ Schematic ...
Page 37: ...AD5934 Rev A Page 37 of 40 05325 146 Figure 42 Linear Regulator on EVAL AD5934EBZ ...
Page 38: ...AD5934 Rev A Page 38 of 40 05325 147 Figure 43 Decoupling on the EVAL AD5934EBZ ...
