Novocontrol Alpha Analyzers Fundamentals

Dirk WilmerNovocontrol Technologies

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Novocontrol Technologies GmbH & Co. KG

Turnkey Dielectric and Impedance Spectrometers

Top-class impedance analyzers with test interfaces for various applications

Reliable sample environment for various temperature ranges and pressure variation

Software for instrument control, automation, and data analysis

Sample cells for a large variety of applications

3

)cos()( 0 tUtu

nT

dttjtinT

I0

* )exp()(2)(

Current harmonic base waveFourier transform over n periods

Voltage

00

** 1)()(

CjUI

Permittivity

Ad

UIj

0

**

0* )()](')([)(

''')tan(,''' 22

0 IIIII

Conductivity

d electrode spacing, A electrode area

capacityempty celldAC 00

Principle of measurement

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Impedance Measurement Requirements for Dielectric Measurements

• Broad frequency range

• Wide impedance range

• Small loss factors tan() = ’’ / ’ = Zs’ / Zs’’

Sample is in first order approximation a capacitor

Capacitive impedance Z = j / (C) Relaxation usually adds small changes in Z DC conductivity adds parallel resistance

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Parallel Representations: Same Voltage in Re, Im

Admittance

Parallel Imp.

Serial Representations: Same Current in Re, Im

Serial Imp.

Loss Factor

)(1

2''2'0

'''

0**

0*

C

jCjI

UZ s

0*

0

** Cj

UIYp

0'

0'''''

* 1111:C

jCY

jY

Zpp

p

'

''

''

'

'

''

)tan(p

p

s

s

ZZ

ZZ

Zs'

Zs''

Zp ' C p '

Zp ' Zp ''

0'

0''

11CC

0'

0''

1 CC

)(

)(

2''2'0

'

2''2'0

''

C

C

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Requirement

Impedance Range

Typical dielectric sample

’ C0 = 100 pF

tan() = 10-4..1

)tan(

'1

'''

0

''

pp

p

ZZ

CZ

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Alpha-A modular measurement system

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Impedance analyzer system highlights• Broad frequency range 3 µHz .. 40 MHz (> 13 decades) • Ultra wide impedance range 10-4 .. 1014 Ω (18 decades)

covers range from conductors to best isolators in a single instrument set-up

• Ultra wide capacity range 10-15 .. 1 F allows broadband measurement of smallest capacities down to 1 fF. 

• High phase accuracy (2.10-3 °) and loss factor tan(δ) absolute accuracy (3.10-5) for low loss dielectric materials and isolators broadband characterization.

• Supports non-linear Dielectric, Conductivity and Impedance Spectroscopy or gain phase measurements in combination with all test interfaces.

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Measurement examples

Alpha totalimpedance range

Typical results covering 18 orders of magnitude dynamics

10-3 10-2 10-1 100 101 102 103 104 105 106 107 108

Frequency [Hz]

10-6

10-2

102

106

1010

1014

1018

Impe

danc

e [O

hms]

Short terminals 0.1 Ohm resistor Open terminals Polyethylene 15 kOhm resistor 100 Ohm resistor 100 GOhm resistor 1 TOhm resistor

10 15

10 -3

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Impedance analyzer system highlights• High speed measurements for online monitoring of time-

dependent processes in the 5 ms range (with Option F)• Automatic self calibration and diagnosis by user

compensates long term internal drift and verifies functionality.

• Precision digital frequency response analyzer up to 40 MHz for two channel gain phase measurements with 0.001° phase - and 10-5 in amplitude resolution included. Operates like a broadband lockin amplifier with two channels, extended accuracy and frequency range.

• Optional control WinDETA software for turnkey calibration, operation, data evaluation, 2- and 3- dimensional graphical representation including non linear spectroscopy.

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Alpha-A: impedance measurements up to 40 MHz

Alpha-AT+ZG4RC network standard test sampleNew Alpha-A signal generatorImproved calibration procedures40 MHz also available for ZG2 and ZGS

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)()(

)exp()(2)(

)cos()(

*0*

0

*

0

kk

NT

k

IUZ

dttjktiNT

I

tUtu

k = 1: first harmonic (or base wave)

Higher harmonics

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HVB 4000: new high voltage test interface for the Alpha-A modular measurement systemDielectrics, semiconductors or electronic components at high AC and/or DC voltages for• non-linear dielectric / impedance spectroscopy; • characterization of materials or components under stress; • extremely high impedance samples exceeding 1014 Ω. Materials measurements: Novocontrol High Voltage Sample Cell Earlier products: - HVB 300 (3 µHz to 1 MHz, 300 Vpp AC and/or DC) - HVB 1000 (3 µHz to 10 kHz, 1000 Vpp AC and/or DC)

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HVB 4000: new high voltage test interface for the Alpha-A modular measurement system•Frequency:  3 µHz ... 10 kHz (9.5 decades)   

•Impedance: 1kΩ .. 2·1015 Ω (12 decades)    •Capacitance:   1 fF ... 0.01 F (13

decades)     •Loss factor tan(δ): 10-5 .. 104

•AC signal out: 30 mV .. 2000 Vp, 2.7 mA max   

•DC bias out: -2000 VDC .. +2000 VDC, 2.7 mA max   

•Output impedance: 750 kΩ    •Voltage in: max. ± 2000 Vp dc coupled

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Electrochemical Impedance Measurements (EIS)• Defined DC Voltage / Current referred to a third (differential) reference electrode

• Potentiostat/Galvanostat function for defined cell DC polarization

• DC measurement

• Superimposed AC voltage / current for impedance measurement

• Classical applications Interface polarization Intrinsic electrolyte conductivity RC Layer structures

• Phase accuracy, impedance range not as critical as for dielectric measurements?

• Additional applications: Ion conductivity, relaxation, sensors, fuel cells

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• Reliable impedance measurements up to 1 MHz• Very wide impedance range: 10-4 up to 1013 • Variable output resistance• Sample protection:high-power counter electrode signal

output supports fast voltage and current limiters independent of the main control loop. Both voltage and current limits continuously adjustable and operate simultaneously in both potentiostat and galvanostat mode.

• Two models: 30 V/2 A and 15 V/10 A

POT/GAL: electrochemical test interfaces for the Alpha-A modular measurement system

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• 4 channel 24 bit digitizer for simultaneous dc signal measurements of the counter-, two reference- and the working electrodes.

• High accuracy working electrode current input converter with reference technique for accurate measurement of both strong conductors and insulators.

• Non-linear EIS by higher harmonic measurements both on instrument and WinDETA application software level.

POT/GAL: electrochemical test interfaces for the Alpha-A modular measurement system

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• Automatic dc level shifters at the working and reference electrodes inputs compensate dc voltage and current offsets in order to accurately measure the small superimposed ac signals for EIS.

• Supports real-time measurements by up to 150 impedance data points / second (option) and 1.500 voltage current data points / second in time domain mode.

POT/GAL: electrochemical test interfaces for the Alpha-A modular measurement system

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An important competitor: specification

• No high-impedance measurements

• Limited phase and tan() resolution

• Limited usabilityat f>10 kHz

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POT/GAL: electrochemical test interfaces for the Alpha-A modular measurement system

4-wire impedance mode accuracy