Circuit Note

CN-0217

Circuits from the Lab™ reference circuits are engineered and

tested for quick and easysystemintegrationto helpsolve today’s

analog, mixed-signal, and RF design challenges. For more

informationand/orsupport,visitwww.analog.com/CN0217.

Devices Connected/Referenced

AD5933

1 MSPS, 12-Bit Impedance Converter,

Network Analyzer

AD5934

250 kSPS, 12-Bit Impedance Converter,

Network Analyzer

AD8606

Precision, Low Noise, Dual CMOS Op Amp

High Accuracy Impedance Measurements Using 12-Bit Impedance Converters

Rev. A

Circuitsfromthe Lab™circuitsfromAnalog Deviceshave been designedandbuiltbyAnalogDevices

engineers. Standard engineering practices have been employed in the design and construction of

eachcircuit,andtheirfunctionandperformancehavebeentestedandverifiedinalabenvironmentat

room temperature. However, you are solely responsible for testing the circuit and determining its

suitabilityandapplicabilityforyouruseandapplication.Accordingly,innoeventshallAnalogDevices

be liable for direct, indirect, special, incidental, consequential or punitive damages due to any cause

whatsoeverconnectedtotheuseofanyCircuitsfromtheLabcircuits. (Continuedonlastpage)

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

www.analog.com

Fax: 781.461.3113

©2011–2013 Analog Devices, Inc. All rights reserved.

EVALUATION AND DESIGN SUPPORT

Circuit Evaluation Boards

AD5933 Evaluation Board (EVAL-AD5933EBZ)

Design and Integration Files

Schematics, Layout Files, Bill of Materials

CIRCUIT FUNCTION AND BENEFITS

The AD5933 and AD5934 are high precision impedance converter

system solutions that combine an on-chip programmable frequency

generator with a 12-bit, 1 MSPS (AD5933) or 250 kSPS (AD5934)

analog-to-digital converter (ADC). The tunable frequency generator

allows an external complex impedance to be excited with a known

frequency.

The circuit shown in Figure 1 yields accurate impedance

measurements extending from the low ohm range to several

hundred kΩ, and it also optimizes the overall accuracy of the

AD5933/AD5934.

50kΩ

50kΩ

50kΩ

50kΩ

20k

Ω

20k

Ω

47nF

+

+

−

−

A1

A2

A1, A2 ARE

½

AD8606

1.48V

1.98V p-p

1.98V p-p

VDD/2

DAC

SCL

SDA

DVDD

AVDD

MCLK

AGND

DGND

VOUT

AD5933/AD5934

RFB

VIN

1024-POINT DFT

INTERFACE

IMAGINARY

REGISTER

REAL

REGISTER

OSCILLATOR

DDS

CORE

(27 BITS)

TEMPERATURE

SENSOR

TRANSMIT SIDE

OUTPUT AMPLIFIER

ADC

(12 BITS)

LPF

GAIN

I-V

Figure 1. Optimized Signal Chain for Impedance Measurement Accuracy (Simplified Schematic, All Connections and Decoupling Not Shown)