AD5934_15 Datasheet, PDF (1/32 Pages) Analog Devices – 250 kSPS, 12-Bit Impedance Converter, Network Analyzer

Data Sheet
250 kSPS, 12-Bit Impedance Converter,
Network Analyzer
AD5934
FEATURES
Programmable output peak-to-peak excitation voltage to a
maximum frequency of 100 kHz
Programmable frequency sweep capability with serial I²C
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 = R² + I ²
Phase = tan^−1(I/R)
A similar device, available from Analog Devices, Inc., is the
AD5933, 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
MCLK
AVDD
DVDD
SCL
SDA
I²C
INTERFACE
REAL IMAGINARY
REGISTER REGISTER
1024-POINT DFT
DDS
CORE
(27 BITS)
DAC
V_BIAS
AD5934
R_OUT
VOUT
Z(ω)
RFB
ADC
(12 BITS)
GAIN
LPF
VIN
VDD/2
AGND
DGND
Figure 1.
Rev. C
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