Tegam 4040A Instruction Manual

4040A

50 MHz PXI Differential

Instrumentation Amplifier

MODEL 4040A

NOTE: This User’s Manual was as current as possible when this product was manufactured. However, products

are constantly being updated and improved. To ensure you have the latest documentation, refer to

www.tegam.com.

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Instruction Manual

PN# 4040A-840

Publication Date: June 2012

REV. E

TABLE OF CONTENTS

TABLE OF CONTENTS

1 INSTRUMENT DESCRIPTION

Instrument Description .............................................................................1-1

Figure 1.1: Block Diagram of the 4040A .................................................1-1

Performance Specifications ........................................................................1-2

Functional Considerations ..........................................................................1-4

Frequency Response Curves ......................................................................1-5

2 PREPARATION FOR USE

Unpacking & Inspection.............................................................................2-1

Safety Information & Precautions ...............................................................2-1

Terms in this Manual ...........................................................................2-1

Terms as Marked on Equipment ............................................................2-1

Grounding the 4040A ...........................................................................2-2

Danger Arising from the Loss of Ground .................................................2-2

Do not Use in Explosive Environments ...................................................2-2

Power Source .....................................................................................2-3

3 OPERATING INSTRUCTIONS

PXI Installation ........................................................................................3-1

Front Panel Description .............................................................................3-2

4 SOFTWARE

5 SERVICE INFORMATION

Cleaning .................................................................................................5-1

Performance Verification Procedure ............................................................5-1

Computer Set-up ................................................................................5-2

CMMR ................................................................................................5-2

Offset Adjustment ...............................................................................5-4

DC Gain .............................................................................................5-6

AC Gain .............................................................................................5-7

Parts Replacement ...................................................................................5-12

Preparation for Calibration or Repair Service ................................................5-12

Expedite Repair and calibration Form ..........................................................5-13

Warranty .................................................................................................5-14

Warranty Limitations ...........................................................................5-14

Statement of Calibration ......................................................................5-14

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I

INSTRUMENT DESCRIPTION

SECTION 1

INSTRUMENT DESCRIPTION

The 4040A is a single channel, differential input amplifier capable of high gain and equally high
attenuation values with a bandwidth from DC-50 MHz. The Model 4040A is capable of operating with
gains of x1, x10, and x100 in conjunction with attenuation by factors of: ÷1, ÷10, and ÷100. These
levels of gain and attenuation may be used in combination to condition a differential input signal so
that it matches the needed input of a low-level device such as a digitizer or oscilloscope. There is a
more in depth explanation contained in the specification section. In addition, the 4040A provides
programmable offset, anti-aliasing filters, input impedance and input coupling. Figure 1.1 is a block
diagram of the 4040A. The 4040A has been specifically designed to take two signals and make a valid
differential measurement by inverting one of the signals and adding the difference, this allows the user
to measure signals not referenced to local ground without compromising safety.

Figure 1.1: Block Diagram of the 4040A

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1-1

INSTRUMENT DESCRIPTION

Net Gain

Input

Attenuation

Internal

Amplifier

Gain

Peak AC Input

Amplitudes

(V) d per
channel

a,b,c,d

Max

Differential

Voltage (V)

w/o clipping

a,b,c,d

Max

Volts to

Chassis

a,b,c

Noise,

Referred to

Input

-3 dB

Bandwidth

÷100

÷100

X1

< 100

< 100

100 V

990 nV/√Hz

20 MHz

÷10

÷10

X1

< 10

< 10

40 V

99 nV/√Hz

20 MHz

÷10

÷100

X10

< 10

< 10

100 V

990 nV/√Hz

50 MHz 1 ÷1

X1

< 1

< 1

4 V

9 nV/√Hz

20 MHz

1

÷10

X10

< 1

< 1

40 V

99 nV/√Hz

50 MHz

1

÷100

X100

< 1

< 1

100 V

990 nV/√Hz

20 MHz

10

÷1

X10

< 0.1

< 0.1

4 V

9 nV/√Hz

50 MHz

10

÷10

X100

< 0.1

< 0.1

40 V

99 nV/√Hz

20 MHz

100

÷1

X100

< 0.01

< 0.01

4 V

9 nV/√Hz

20 MHz

a. DC Coupled, 1 MΩ input
b. AC Coupled, 1 MΩ input: DC + Peak AC not to exceed 100 V; Peak AC component not to exceed table
c. 5 Vrms max into 50 Ω
d. DAC offset adjustment to zero

PERFORMANCE SPECIFICATIONS

The multiple gain and attenuation settings of the 4040A interact to affect the performance in terms of
bandwidth and noise. Table 1.1 shows the various combinations and how these settings modify what
can be expected from the 4040A.

Table 1.1: Various Combination Possibilities of the 4040A

As an example, a total system gain of X1 can be achieved three different ways depending on the signal
requirements through attenuating and amplifying by different amounts. Choosing the best combination
involves trade offs in input amplitude, bandwidth and signal to noise ratio. Noise increases with higher
levels of attenuation because the noise specification is referred to the input. In relative terms the
signal to noise ratio is basically constant.

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INSTRUMENT DESCRIPTION

Input Specifications Value Clarification

Channels Single Channel Differential Input
Gains 100, 10, 1, 0.1, 0.01
Maximum Voltage Range ±100 V DC + Peak AC
Coupling AC, DC In AC 10 Hz and above
Input Impedance 1 MΩ | | 20 pF, 50 Ω ±1%, Selectable
Input Voltage Range ±100 V For Gain 0.01 @ 1 MΩ Input Impedance

±10 V For Gain 0.1 @ 1 MΩ Input Impedance
±5 V For Gain 0.1 @ 50 Ω Input Impedance
±1 V For Gain 1
±0.1 V For Gain 10
±0.01 V For Gain 100

Connection Type BNC Jacks 50 Ω, Quantity 2

Common Mode Rejection Ratio
(CMRR) 77 dB at 60 Hz For Gain setting of x1, x10 and x100 & Attenuation
(> 50 dB at 1 MHz) setting of ÷1
57 dB at 60 Hz For Attenuation setting of ÷10
37 dB at 60 Hz For Attenuation setting of ÷100

Total Harmonic Distortion <-60 db @ 1 MHz Output 1 Vp-p into 50 Ω
DC Gain Accuracy ± (0.1% |input| + 100 µV) Offset set to 0 for Gain 10, 1, 0.1, 0.01

± (1.5% |input| + 300 µV) Offset set to 0 for Gain 100
(Basic) AC Gain Accuracy ±0.15 dB Attenuation of 1, Gain of 1,

See Figures 1.2, 1.3 and 1.4 for other settings
Over-voltage Protection ±100 V DC + Peak AC

(In Any Range)
Offset Range 0 to ± Full Scale Full Scale output of ±1 V into 50 Ω,

All Gain Ranges
Offset Resolution 38 µV per step 65,535 total DAC steps into 50 Ω
Offset Accuracy ±(0.5% of |Setting| + 300 µV) Referenced to 1 V Range
Temperature Stability ±(0.01% of |rdg| + 40 µV)/°C All Gain Ranges
Noise 9 nV/√Hz CMR=±1 V, Gain 10 and 100

Referred to Input for Frequencies >100 Hz
Rise Time ≤3.5 ns

Output Specifications Value Clarifications

Maximum Output Voltage ±1 V Single Ended into 50 Ω
Connection Type SMB Jack 50 Ω
Output Impedance 50 Ω ±1%
LP Filter, Cutoff Frequency 100 kHz, 1 MHz Single Pole Filter
Bandwidth See Table 1.1
Passband Flatness See Figures 1.2, 1.3 and 1.4 Limits off charts will not exceed ±3 dB for the

for limits Bandwidths listed in Table 1.1

Environmental
Specifications Value

Operating Temperature 0 °C to +45 °C, (32 °F to 113 °F) Ambient
Storage Temperature -20 °C to +50 °C (-4 °F to +122 °F)
Humidity Range <80% RH Non-Condensing
Warm-up Time 30 minutes

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INSTRUMENT DESCRIPTION

Functional Considerations

Voltage & Current Limitations

In general, the maximum input voltage of the 4040A should not exceed ±100 V (200 Vp-p) when the

input terminator is set to 1 MΩ. However, some settings will produce incorrect results at lower

voltages. This occurs when the input signal or gain setting is too high and causes the output amplifier
to clip the signal. An example of this would be measuring a 10 V signal with the gain set to x100.
Mathematically this results in a 1000 V signal which clearly exceeds the 2 Vp-p rating of the output
amplifier. See Table 1.1 for a table of appropriate input voltages for given combinations of gain and
attenuation. No damage would occur to the 4040A or to a digitizer connected to it if the input range
was exceeded, but the signal would be distorted. A signal in excess of 100 V would cause the onboard
voltage limiting circuitry to activate and also create distortion.
There are other considerations when the 4040A is configured with the 50 Ohm input termination. The
input voltage is limited to a maximum of ±5 Vrms. This is due to the power limitations of the
terminator which is 2 W. To preserve the signal integrity and bandwidth of the amplifier the 50 Ohm
terminator is protected with surface mount single use fuses.
Important: Exceeding the rating of the input in this case requires the 4040A to be returned to the
factory for service.

Frequency Characteristics

The 4040A is capable of amplifying mill-volt level signals with a bandwidth from DC to 50 MHz. Some
combinations of gain and attenuation will limit the bandwidth to 20 MHz. See Table 1.1 for a complete
list of settings and the expected bandwidth. In addition, AC coupling rolls off the low frequencies at 10
Hz.
Two anti-aliasing low pass filters are included and tuned for 100 KHz and 1 MHz. These are first order
filters that roll off at 20 dB per decade.

Offset Adjustment

The 4040A includes a programmable offset adjustment that operates on the signal after the gain
stage. The resolution of the adjustment is 38 µV and can offset the signal ±1 V which is the entire
range of the output amplifier. It is not able to effectively offset a signal that exceeds the input range of
a given gain and attenuation setting.

Selecting Gains and Ranges

The amplitude of the signal being measured is the primary consideration when selecting the
appropriate gain and attenuation settings. As an example: A 100 mV signal that is riding on 42 V can
be effectively measured with an attenuation setting of ÷100 and a gain setting of x10. This is because
the differential operation of the 4040A rejects the 42 V common mode signal and only amplifies the
difference producing an output signal of 1 V. If the signal of interest was the 42 V itself the 4040A
should be configured with an attenuation of ÷100 and a gain of x1 producing an output signal of 0.42
V. The 4040A attenuates the signal prior to amplification.

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INSTRUMENT DESCRIPTION

Gain Deviation from Nominal (No Attenuation)

(Typical Data and Test Limits)

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08

Frequency (Hz)

Gain Error (dB)

1/1 Li mit

10/1 Li mi t

100/1 Li mi t

1/1 POS

1/1 NEG

10/1 POS

10/1 NEG

100/1 POS

100/1 NEG

Figure 1.2: Frequency Response Curves

Figure 1.2 depicts the typical frequency response curves from the nominal gain values with no
attenuation applied by the 4040A. The three different black bands, above and below the curves, give
the allowable limits for passband flatness for the different gain/attenuation settings. Individual plots
are given for both the positive and negative inputs of the 4040A for all gain/attenuation settings. For
example, to find the expected passband flatness from 10 kHz to 10 MHz to achieve an inverted gain of
100, the 100/1 NEG plot would be used in conjunction with the solid black limit lines. These lines are
used because the first number is for the gain, and the second number is for attenuation, POS for
positive, and NEG for negative. The expected passband flatness would be ±0.25 dB from 10 kHz to 6
MHz and +0.25 dB to -3 dB from 6 MHz to 10 MHz.

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INSTRUMENT DESCRIPTION

Gain Deviation from Nominal ÷10 Attenuation

(Typical Data and Test Limits)

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08

Frequency (Hz)

Gain Error (dB)

1/10 Li mi t

10/10 Li mi t

100/10 Limi t

1/10 POS

1/10 NEG

10/10 POS

10/10 NEG

100/10 POS

100/10 NEG

Figure 1.3 depicts the typical frequency response curves from the nominal gain values with an
attenuation of 10 applied by the 4040A. As with Figure 1.2, the three different black bands, above and
below the curves, give the allowable limits for passband flatness for the different gain/attenuation
settings. Individual plots are given for both the positive and negative inputs of the 4040A for all
gain/attenuation settings. For example, to find the expected passband flatness from 1 kHz to 7 MHz to
achieve an inverted gain of 10, the 100/10 NEG plot would be used in conjunction with the solid black
limit lines. These lines are used because the first number is for the gain, and the second number is for
attenuation, POS for positive, and NEG for negative. The expected passband flatness would be ±0.3 dB

from 1 kHz to 5 MHz and +0.3 dB to -3 dB from 5 MHz to 7 MHz.

Figure 1.3: Frequency Response Curves

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INSTRUMENT DESCRIPTION

Gain Deviation from Nominal ÷100 Attenuation

(Typical Data and Test Limits)

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08

Frequency (Hz)

Gain Error (dB)

1/100 Li mi t

10/100 Limi t

100/100 Limi t

1/100 POS

1/100 NEG

10/100 POS

10/100 NEG

100/100 POS

100/100 NEG

Figure 1.4: Frequency Response Curves

Figure 1.4 depicts the typical frequency response curves from the nominal gain values with an
attenuation of 100 applied by the 4040A. As with Figure 1.2 & 1.3, the three different black bands,
above and below the curves, give the allowable limits for passband flatness for the different
gain/attenuation settings. Individual plots are given for both the positive and negative inputs of the
4040A for all gain/attenuation settings. For example, to find the expected passband flatness from 100
kHz to 25 MHz to achieve a gain of 1, the 100/100 POS plot would be used in conjunction with the
solid black limit lines. These lines are used because the first number is for the gain, and the second
number is for attenuation, POS for positive, and NEG for negative. The expected passband flatness
would be ±0.3 dB from 100 kHz to 5 MHz and +0.3 dB to -3 dB from 5 MHz to 20 MHz. 20 MHz is the
bandwidth limit for the 4040A in this setting. If 25 MHz is needed a setting of 10/10 or 1/1 can be
used as long as the input voltages for those ranges are not exceeded.

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1-7