Gamry Reference 600+ User manual

Reference 600+
Potentiostat/Galvanostat/ZRA
Operator’s Manual
Copyright 2018 Gamry Instruments, Inc.
Revision 6.2
January 9, 2018
988-00006

2

1
If You Have Problems
Please visit our service and support page at www.gamry.com/service-support/. This page contains information
on installation, software updates, and training. It also contains links to the latest available documentation. If you
are unable to locate the information you need from our website, contact us via email using the link provided
on our website. Alternatively, you can contact us one of the following ways:
Internet www.gamry.com/service-support/
Telephone [phone]:00 AM–5:00 PM US Eastern Standard Time
[phone] Toll Free US & Canada Only
Please have your instrument model and serial numbers available, as well as any applicable software and
firmware revisions.
If you have problems in installation or use of a system containing a Reference 600+, please try to call from a
telephone next to your computer, where you can type and read the screen while talking to us.
We will be happy to provide a reasonable level of free support for registered users of the Reference 600+
Potentiostat/Galvanostat/ZRA. Reasonable support includes telephone assistance covering the normal
installation, use, and simple customization of a computerized system containing a Reference 600+ connected
to a Windows®-compatible computer.
A service contract that extends both the hardware warranty and software update period is available at an
additional charge. Software updates do not include software enhancements offered to our customers at
additional cost.
Enhancements to the Reference 600+ and Gamry’s standard applications software that require significant
engineering time on our part can be performed on a contract basis. Contact us with your requirements.

2
Limited Warranty
Gamry Instruments, Inc. warrants to the original user of this product that it shall be free of defects resulting from
faulty manufacture of the product or its components for a period of two years from the original shipment date
of your purchase.
Gamry Instruments, Inc. makes no warranties regarding either the satisfactory performance of the Reference
600+ Potentiostat/Galvanostat/ZRA including the software provided with this product or the fitness of the
product for any particular purpose. The remedy for breach of this Limited Warranty shall be limited solely to
repair or replacement, as determined by Gamry Instruments, Inc., and shall not include other damages.
Gamry Instruments, Inc. reserves the right to make revisions to the system at any time without incurring any
obligation to install same on systems previously purchased. All system specifications are subject to change
without notice.
There are no warranties which extend beyond the description herein. This warranty is in lieu of, and
excludes any and all other warranties or representations, expressed, implied or statutory, including
merchantability and fitness, as well as any and all other obligations or liabilities of Gamry Instruments,
Inc., including but not limited to, special or consequential damages.
This Limited Warranty gives you specific legal rights and you may have others, which vary from state to state.
Some states do not allow for the exclusion of incidental or consequential damages.
No person, firm or corporation is authorized to assume for Gamry Instruments, Inc., any additional obligation
or liability not expressly provided herein except in writing duly executed by an officer of Gamry Instruments,
Inc.

3
Disclaimers
Gamry Instruments, Inc. cannot guarantee that the Reference 600+ Potentiostat/Galvanostat/ZRA will work
with all computer systems, operating systems, and third-party software applications hardware/software.
The information in this manual has been carefully checked and is believed to be accurate as of the time of
printing. However, Gamry Instruments, Inc. assumes no responsibility for errors that might appear.
Copyrights
Reference 600+  Potentiostat/Galvanostat/ZRA Operator’s Manual, copyright 2007–2018, Gamry
Instruments, Inc., all rights reserved.
Gamry Framework copyright 1989–2018, Gamry Instruments, Inc., all rights reserved.
Reference 600+, ECM8, Interface 1010, Gamry Framework, and Gamryare trademarks of Gamry
Instruments, Inc.
Windows is a registered trademark of Microsoft Corporation. Intel is a trademark of Intel Corporation in the
U.S. and/or other countries.
No part of this document may be copied or reproduced in any form without the prior written consent of
Gamry Instruments, Inc.

4

1
Table of Contents
Chapter 1: Safety Considerations ................................................................................................... 3
Inspection ........................................................................................................................ 3
Product Safety.................................................................................................................. 3
AC Mains Connection to the Power Brick ......................................................................... 3
Grounding in the Reference 600+ ................................................................................... 4
Operation with Earth-Grounded Cells and Auxiliary Apparatus.......................................... 5
Temperature and Ventilation ............................................................................................ 5
Defects and Abnormal Stresses ......................................................................................... 6
Environmental Limits ........................................................................................................ 6
Cleaning........................................................................................................................... 6
Service ............................................................................................................................. 7
RF Warning ...................................................................................................................... 7
Electrical Transient Sensitivity ........................................................................................... 7
CE Compliance ................................................................................................................ 8
RoHS Compliance............................................................................................................ 8
Chapter 2: Introduction................................................................................................................. 9
About this Manual ............................................................................................................ 9
About the Reference 600+ .............................................................................................. 9
Notational Conventions .................................................................................................... 10
Chapter 3: Instrument Circuitry ..................................................................................................... 11
Reference 600+ Schematics and Block Diagrams ............................................................. 11
Chapter 4: Installation ................................................................................................................... 19
Initial Visual Inspection..................................................................................................... 19
Physical Location.............................................................................................................. 20
Computer Requirements .................................................................................................. 20
Quick-start Guide for System Installation .......................................................................... 21
Software Installation ......................................................................................................... 21
Reboot your Computer after Software Installation ............................................................. 21
Power Cord and Power Connection.................................................................................. 22
Power-up Test.................................................................................................................. 23
USB Cables ...................................................................................................................... 23
Front Panel USB LED........................................................................................................ 24
Cell Cable Installation....................................................................................................... 24
Multiple Potentiostat Systems ........................................................................................... 25
First-time Device Installation in Windows®........................................................................ 25
Running the Framework ................................................................................................... 25
Framework Device Status Bar ........................................................................................... 25
Gamry Instrument Manager .............................................................................................. 26
Blink Button ..................................................................................................................... 29
Changing the Label........................................................................................................... 29
The Reference 600+ Customization Label........................................................................ 30
Chapter 4: Calibration ................................................................................................................... 33
Introduction ..................................................................................................................... 33
Instrument DC and AC Calibration ................................................................................... 33
Cable Calibration ............................................................................................................. 35
Low I Range DC Calibration ............................................................................................. 37
Chapter 5: Cell Connections.......................................................................................................... 39
Normal Cell Connections.................................................................................................. 39
ZRA Mode Cell Connections ............................................................................................ 40

2
Membrane Cell Connections ............................................................................................ 41
Chapter 6: Panel Indicators and Connectors .................................................................................. 43
Front Panel....................................................................................................................... 43
Rear Panel........................................................................................................................ 46
Chapter 7: Stability in Potentiostat Mode....................................................................................... 53
Capacitive Cells and Stability ............................................................................................ 53
Improving Potentiostat Stability......................................................................................... 53
Chapter 8: Measurement of Small Signals ...................................................................................... 57
Overview ......................................................................................................................... 57
Measurement System Model and Physical Limitations ....................................................... 57
Hints for System and Cell Design ...................................................................................... 61
Floating Operation ........................................................................................................... 63
Appendix A: Reference 600+ Specifications.................................................................................. 65
Appendix B: Reference 600+ Cell Cable Connector ...................................................................... 71
Appendix C: Misc. I/O Connector.................................................................................................. 73
Appendix D: Auxiliary A/D Input Characteristics ............................................................................ 75
Aux A/D Specifications ..................................................................................................... 75
Function Call to Set the Aux A/D BNC Characteristics ....................................................... 75
Appendix E: CE Certificate............................................................................................................. 77
Declaration of Conformity ................................................................................................ 77
Certificate of Conformance............................................................................................... 79
Comprehensive Index.................................................................................................................... 80

3
Chapter 1: Safety Considerations
Your Reference 600+ Potentiostat/Galvanostat/ZRA has been supplied in a safe condition. This chapter of
the Reference 600+ Operator’s Manual contains some information and warnings that you must follow to
ensure continued safe operation of the Reference 600+.
Inspection
When you receive your Reference 600+ Potentiostat/Galvanostat/ZRA, inspect it for evidence of shipping
damage. If you find any damage, please notify Gamry Instruments Inc. and the shipping carrier
immediately. Save the shipping container for possible inspection by the carrier.
Product Safety
The Reference 600+ has been designed, tested and certified to meet the requirements of EN 61010,
Safety requirements for electrical equipment for measurement, control, and laboratory use. As defined in
this standard, it is a Category II apparatus, with any “hazardous live voltages”protected by “reinforced
insulation”.
Most of the Reference 600+ circuitry operates at voltages low enough to be considered safe. The
Reference 600+ contains a limited amount of internal circuitry that is at “hazardous live” voltages as
defined in EN 61010 (the standard mentioned above). “Reinforced insulation” (again defined in EN 61010)
is used to reduce the risk of electrical shock due to this “hazardous live” voltage.
The majority of the Reference 600+’s circuitry does not contain voltages higher than 30 V DC. As a
generalization, input and output voltages in the Reference 600+ are limited to 24 V. This voltage level is
considered safe.
The “AC Adapter” supplied with the Reference 600+ is certified under EN 60950. The AC Adapter
converts the AC mains voltage to 24 V DC, which is used to power the Reference 600+.
Always use the AC adapter (power brick) supplied with your Reference 600+ to supply DC power to the
instrument.
AC Mains Connection to the Power Brick
The Reference 600+ does not connect directly to an AC Mains supply. Instead, the mains are connected
to desktop AC adapter (power brick), which outputs 24 V DC and in turn powers the Reference 600+.
Warning: A Reference 600+ damaged in shipment can be a safety hazard. Do not
operate damaged apparatus until a qualified service technician has verified its safety. Tag a damaged
Reference 600+ to indicate that it could be a safety hazard.
Caution: Do not use a DC power source other than the AC adapter model provided
with your Reference 600+. Other replacements may void the performance and/or safety characteristics
of the Reference 600+.

4
The Reference 600+ is normally provided with an AC line cord suitable for your location. This AC line
cord connects the AC mains to the AC power adapter. If your Reference 600+ has been provided without
an AC line cord, or a cord that is not compatible with your local AC mains socket, obtain a line cord
certified for use in your country. Contact your local Gamry Representative or email to
[e-mail] if you are uncertain what AC line cord to use.
Grounding in the Reference 600+
The circuitry and the metal case of the Reference 600+ are not connected to an earth ground. If they
were connected to earth ground, it would compromise the Reference 600+’s ability to make
measurements in electrochemical cells that contain earth grounded metal. A few examples of such cells
include autoclaves, metallographic stress apparatus, and detectors for capillary electrophoresis.
Most electrochemical cells are isolated from earth ground, so isolation of the Reference 600+ from earth is
not required. In these cases, connection of the Reference 600+ chassis to an earth ground may lower the
noise seen in an electrochemical test. A Chassis Ground binding post on the rear panel of the Reference
600+ makes for easy implementation of this connection. Simply run a wire from this binding post to a
suitable source of earth ground. A black 1.2-meter wire is provided with the Reference 600+ to ease this
connection.
Note this connection of the Reference 600+ to an earth ground is not a “Protective Earth Ground” as
defined in EN 61010. The Reference 600+ is safe in the absence of this connection.
The Reference 600+’s AC Adapter is rated for operation from 100 to 240 V AC, 47 to 63
Hz. It should therefore be useful throughout the world.
Sources of earth ground include
• Most metal water pipes,
• The chassis of most electronic apparatus (which are generally earth-grounded), and
• The protective ground terminal of an AC mains power plug.
We recommend that you discuss grounding with an electrical or electronics professional prior to
making this earth-ground connection.
Warning: Do not connect the chassis ground binding post to any voltage other than
earth ground. An improper connection can create a safety hazard, which could result in personal injury
or death.

5
Operation with Earth-Grounded Cells and Auxiliary Apparatus
As described above, the Reference 600+ circuitry is isolated from earth ground, allowing it to make
measurements on cells that include an earth ground. This ground isolation is often called floating
operation. Cells with earth ground include many autoclaves, pipelines and storage tanks, and many fuel
cell systems.
Connection of the Reference 600+ to auxiliary apparatus will often earth-ground the Reference 600+
destroying its ability to float and make measurements on earth-grounded cells. Connection of the Monitor
BNCs to an oscilloscope is an example where the instrument is earthed.
The User I/O connector can be connected to earth-grounded apparatus without earth-grounding the
Reference 600+, if the cabling is done carefully. The metal shell on the Reference 600+ User I/O
Connector is connected to the instrument’s chassis which is a floating ground. In a system that needs
isolation from earth ground, the shield of your I/O cable must not connect the D-connector’s metal shell to
earth ground. Reference all user I/O signals to pin 6 of the D-connector, which is earth ground on the
Reference 600+.
The Reference 600+ contains spark-gap surge suppressors that limit the voltage difference between the
Reference 600+’s chassis ground and earth ground to about 90 V. These surge suppressors are not part of
the safety mechanisms in the Reference 600+. Instead they are present to limit the possibility of improper
instrument operation or instrument damage caused by electrostatic discharge (static electricity) and other
surge events such as lightning.
Temperature and Ventilation
Your Reference 600+ Potentiostat/Galvanostat/ZRA was designed for indoor use at ambient temperatures
between 0°C and 45°C.
The Reference 600+ uses forced air-cooling to keep its electronic components within their operating
temperature range. Air is drawn into the Reference 600+ chassis through slots located on the sides of the
chassis near the front panel. The air exits through the two fans at the rear of the unit.
Caution: Floating operation of the Reference 600+ can be compromised by improper
cables to your I/O Connector. We do not recommend use of standard 15-pin shielded cables with this
connector. Custom cables with the shield connected to pin 6 of the D-connector are preferred.
Warning: Do not connect the chassis ground binding post to any voltage other than
earth ground. An improper connection can create a safety hazard, which could result in personal injury
or death.

6
Be careful when operating the Reference 600+ in an enclosed space (such as an enclosed relay rack or
NEMA enclosure). The temperature within the enclosure must not exceed 45°C. You may need to provide
ventilation holes or even forced-air cooling for the enclosed space if excessive temperature rise occurs.
Defects and Abnormal Stresses
Treat your Reference 600+ as potentially hazardous if any of the following is true of the unit:
•It shows visible damage,
•It does not operate properly,
•It has been stored for a long period of time under unfavorable conditions,
•It has been dropped or subjected to severe transport stress,
•It has been subjected to environmental stress (corrosive atmosphere, fire, etc.).
Do not use your Reference 600+ or any other apparatus if you think it could be hazardous. Have it
checked by qualified service personnel.
Environmental Limits
There are environmental-limit conditions on the storage, shipping and operation of this equipment. The
Reference 600+ has not been designed for outdoor use.
Storage
Ambient Temperature
–40°C to 75°C
Relative Humidity
Maximum 90% non-condensing
Shipping
Same as storage plus
Acceleration
Maximum 30 G
Operation
Ambient Temperature
0°C to 45°C
Relative Humidity
Maximum 90% non-condensing
Cleaning
Disconnect the Reference 600+ from all power sources prior to cleaning.
Caution: Do not block the airflow into or out of the Reference 600+ chassis. While the
circuitry should suffer no damage caused by excessive heat, the Reference 600+ enclosure may
become uncomfortably hot to the touch if insufficient air flows through the chassis. Running the
Reference 600+ without adequate cooling could shorten the time to failure of some of the circuitry.
Warning: The Reference 600+ is not designed for operation in conditions where liquid
water may enter the chassis, or water vapor may condense within the chassis. Operation of a Reference
600+ that has water within the chassis can create a safety hazard, which could result in personal injury
or death.

7
Use a cloth lightly dampened with either clean water or water containing a mild detergent, to clean the
outside of the Reference 600+ enclosure. Alternatively, you may use isopropyl alcohol. Do not use a wet
rag or allow fluid to enter the Reference 600+ enclosure. Do not immerse the Reference 600+ in any type
of cleaning fluid (including water). Do not use any abrasive cleaners.
Service
Your Reference 600+ Potentiostat/Galvanostat/ZRA has no user-serviceable parts inside. Refer all service to
a qualified service technician.
RF Warning
Your Reference 600+ Potentiostat/Galvanostat/ZRA generates, uses, and can radiate radio-frequency
energy. The radiated levels are low enough that the Reference 600+ should not create an interference
problem in most industrial laboratory environments.
The Reference 600+ has been tested for both radiated and conducted RF interference and has been found
to be in compliance with FCC Part 18 and EN 61326:1998—Electrical equipment for measurement,
control, and laboratory use—EMC Requirements.
Electrical Transient Sensitivity
Your Reference 600+ Potentiostat/Galvanostat/ZRA was designed to offer reasonable immunity from
electrical transients, including transients on the incoming AC mains supply and electrostatic discharge. It
has been tested for compliance with EN 61326:1998—Electrical equipment for measurement, control, and
laboratory use—EMC Requirements describing acceptable limits for electrical transient susceptibility in
laboratory test equipment. The Reference 600+ is not rated for continuous use when subject to ESD
events. It should suffer no permanent damage when subject to the standard ESD events defined in
EN61326, but may cease normal operation until it is powered down and restarted.
In severe cases, the Reference 600+ could malfunction as a result of electrical transients such as a static
discharge. If you are having problems in this regard, the following steps may help:
If the problem is static electricity (sparks are apparent when you touch the Reference 600+ or its cables):
•Try placing your Reference 600+ on a static-control work surface. Static-control work surfaces are
now generally available from computer-supply houses and electronics-tool suppliers. An antistatic
floor mat may also help, particularly if a carpet is involved in generating the static electricity.
•Air ionizers or even simple air humidifiers can reduce the voltage available in static discharges.
•If the problem is AC power-line transients (often from large electrical motors near the Reference
600+):
•Try plugging your Reference 600+ into a different AC power branch circuit.
•Plug your Reference into a power-line surge-suppressor. Inexpensive surge-suppressors are now
generally available because of their use with computer equipment.
Contact Gamry Instruments, Inc. if these measures do not solve the problem.
Warning: Never operate the Reference 600+ with any cover or panel on the
chassis open. Dangerous voltages may be present at several points within the Reference 600+ chassis,
including PC board traces. Always remove the power connection before opening the Reference 600+
case.

8
CE Compliance
The European Community has instituted standards limiting radio frequency interference emitted by
electronic devices, setting limits for susceptibility of apparatus to RF energy and transient events, and
mandating safety requirements. Gamry Instruments, Inc. has designed and tested the Reference 600+ to
comply with these standards.
The relevant CE regulations include EN 61010 and EN 61326.
RoHS Compliance
The Reference 600+ has been built using lead-free components and lead-free solder. It is in compliance
with the European RoHS initiative.

9
Chapter 2: Introduction
About this Manual
This manual covers the installation, safety, and use of the Gamry Instruments Reference 600+
Potentiostat/Galvanostat/ZRA.
This manual describes use of a Reference 600+ with Revision 7.0 (and later revisions) of the Gamry
Framework software. It is equally useful when setting up a newly-purchased potentiostat or modifying the
setup of an older potentiostat for use with new software.
Chapter 1 was an in-depth discussion of safety issues. This chapter describes this manual and gives a brief
overview of the Reference 600+ features. Chapter 3 is a description of the electronic circuitry in the
Reference 600+. Chapter 4 contains Reference 600+ installation instructions. Chapter 5 describes cell
cable-connections and Chapter 6 describes the Reference 600+’s front and rear panels. Chapter 7 covers
the difficult issues of potentiostat stability and approaches to prevent oscillation. Chapter 8 discusses the
realities of low-current, high-impedance measurements.
Dry technical material such as specifications and connector pin-outs is in the Appendices.
This manual does not discuss software installation or software operation in any detail.
Software support for the Reference 600+ is described in the Gamry Framework’s Help system.
All the Gamry Instruments’ applications running under the Gamry Framework control the Reference 600+
via a PSTAT object. See the Framework Help system for information concerning PSTAT objects and their
functions.
About the Reference 600+
The Reference 600+ Potentiostat is a research-grade electrochemical instrument packaged in a small,
easy-to-handle case. It offers measurement capabilities similar to instruments that are more than ten times
its size and weight and more than twice its price. The Reference 600+ can operate as a potentiostat, a
galvanostat, or a ZRA (zero-resistance ammeter).
Reference 600+ features include:
•Eleven-decade current auto-ranging,
•Electrical isolation from earth ground,
•Current-interrupt iR compensation, and
•Both analog and digital filtering.
A sine-wave generator on the Reference 600+ allows its use for impedance measurements at frequencies
up to 5 MHz. Data can be acquired at frequencies up to 300 000 points per second, allowing cyclic
voltammetry at scan rates of 1500 V/s with a resolution of 5 mV per point.
A unique DSP (Digital Signal Processing) data-acquisition mode allows the Reference 600+ to reject noise
from the instrument itself, from the electrochemical cell, and from the lab environment. In many cases
where other instruments require a cell in a Faraday shield to make quiet measurements, the Reference
600+ can be used with the cell exposed on a bench top.
The Reference 600+ offers an unprecedented combination of high speed, high sensitivity, and low noise.
At the time this is written, the Reference 600+ offers the widest EIS performance area (in a plot of
impedance versus frequency) of any Potentiostat. State-of-the-art analog components were used
throughout the design. In all design decisions, performance weighed more heavily than product cost.

10
The Reference 600+, like all Gamry potentiostats, requires a computer for its use. Unlike our older
potentiostats, the Reference 600+ connects to the computer through a USB connection. The USB
connection has become truly universal, with USB ports found on all modern computers. Gamry’s software
currently supports up to 16 Reference 600+ Potentiostats connected to one computer.
The Reference 600+ is isolated from earth ground. It can therefore be used to make measurements on
cells that contain an earth-grounded metal. A few of the many examples of such systems are autoclaves,
large metal storage tanks, stress apparatus, and capillary electrophoresis detectors.
Notational Conventions
In order to make this manual more readable we have adopted some notational conventions. These are
used throughout this manual and all other Gamry Instruments manuals:
•Numbered lists. A numbered list is reserved for step-by-step procedures, with the steps always
performed sequentially.
•Bulleted list. The items in a bulleted list, such as this one, are grouped together because they
represent similar items. The order of items in the list is not critical.
•File names and folders. Inside paragraphs, references to computer files and Windows®folders are
capitalized and placed within quotes, for example: “C:\MYGAMRYDATA\CV.DTA” and
“GAMRY5.INI”.

11
Chapter 3: Instrument Circuitry
Reference 600+ Schematics and Block Diagrams
If you are not familiar with electronic schematics or potentiostats, you probably want to skip this chapter.
This information is for expert use only and is not required for routine use of the Reference 600+.
The following figures are partly schematic diagrams and partly block diagrams. They are intended to show
the basic principles of the Reference 600+ without the confusion of the full circuitry details. The
complexity of the Reference 600+ can be quite daunting: the Reference 600+ circuit boards contain
more than 2500 components connected by almost 2000 circuit nets!
The schematic/block diagram figures show:
•The potentiostat board in its potentiostatic control mode,
•The control-board circuits for signal generation,
•The control-board circuits for signal conditioning and A/D conversion,
•The Auxiliary ADC channel-input switching,
•The processors in the Reference 600+, and
•DC-DC power conversion.

12
Figure 3-1
Reference 600+ Potentiostat Board in Potentiostat Mode
Simplified Schematic/Block Diagram

13
Notes for Figure 3-1
•Only Potentiostat Mode circuitry is shown in this figure. In this mode the voltage difference
between the Reference and Working Sense leads (called Esig) is feedback into the control
amplifier.
In Galvanostat Mode, the feedback is from Isig.
In ZRA mode, the feedback is from a differential amplifier measuring the difference between the
Counter Sense and Working Sense leads of the cell cable. The counter sense circuitry is not
shown. It is conceptually similar to the voltage-sensing circuit that generates Esig.
•The Bias DAC and PFIR (Positive Feedback IR compensation) DAC are set using a computer bus
that is not shown.
•Switches are either reed relays or MOS switches as appropriate. All switches are under computer
control (obviously, because the Reference 600+ does not have a knob-and-dial front panel).
•All components shown as being variable (resistance Rm, capacitor IEStab and capacitor CASpeed)
are actually several fixed-value components switched into the circuit. They are not continuously
variable as implied in the figure.
•The monitor BNC connectors for Isig and Esig are lightly filtered using an RLC circuit.
•The programmable attenuator on Esig prior to the ADC channel scales Esig so that it is compatible
with the A/D channel’s 3 V input range. The 0.25 gain setting allows the Reference 600+ to
measure potential signals slightly in excess of 10 V (on a 12 V full-scale range). Isig is gained to be
3 V full-scale so it does not require a similar attenuation function.
•All the resistors summing voltages into the Control Amplifier input do not have values shown; their
values depend on scaling factors too complex to discuss in this simplified diagram.
•Calibration components are not shown.
•Gamry’s software can disconnect the signal generator from the Potentiostat. Once disconnected it
can be used for other experimental control tasks.
•Overload protection and overload detection are not shown. Good engineering practice demands
that any possible misconnection of the cell leads will not damage the instrument. This practice has
been followed in the Reference 600+ design.

14
Figure 3-2
Reference 600+ Signal Generation Circuitry
Notes on Figure 3-2:
•All the resistors summing voltages into the Summing Amplifier input do not have values shown
because their values depend on scaling factors too complex for this simplified diagram.
•The IR DAC has a 8 V full-scale range.
•Calibration components are not shown.
•The DDS can generate fixed-amplitude sine waves with frequencies between 5 MHz and 1 mHz.
In practice, Gamry’s EIS software uses the Scan DAC to generate sine signals if frequency is below
1 Hz.
The low-pass filter removes high-frequency distortion in the “raw” DDS output.
The attenuator scales the DDS. The maximum output signal is 4.096 V peak-to-peak and the
minimum is approximately 20 V peak-to-peak.
•The BNC connector for Sig Gen out is lightly filtered using an RLC circuit.