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that in all previously published material. Specifications and price change privileges reserved.
TEKTRONIX, TEK and TekConnect are registered trademarks of Tektronix, Inc.
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Contacting Tektronix
Tektronix, Inc.
14200 SW Karl Braun Drive
P.O. Box 500
Beaverton, OR 97077
USA
For product information, sales, service, and technical support:
HIn North America, call 1-800-833-9200.
HWorldwide, visit www.tektronix.com to find contacts in your area.
Table of Contents
General Safety Summaryiii...................................
Review the following safety precautions to avoid injury and prevent damage to
this product or any products connected to it. To avoid potential hazards, use this
product only as specified.
Only qualified personnel should perform service procedures.
While using this product, you may need to access other parts of the system. Read
the General Safety Summary in other system manuals for warnings and cautions
related to operating the system.
ToAvoidFireor
Personal Injury
Connect and Disconnect Properly. Connect the probe output to the measurement
instrument before connecting the probe to the circuit under test. Disconnect the
probe input from the circuit under test before disconnecting the probe from the
measurement instrument.
Observe All Terminal Ratings. To avoid fire or shock hazard, observe all ratings
and markings on the product. Consult the product manual for further ratings
information before making connections to the product.
Do not apply a potential to any terminal, including the common terminal, that
exceeds the maximum rating of that terminal.
Do Not Operat e Without Covers. Do not operate this product with covers or panels
removed.
Avoid Exposed Circuitry. Do not touch exposed connections and components
when power is present.
Do Not Operate With Suspected Failures. If you suspect there is damage to this
product, have it inspected by qualified service personnel.
This section discusses operating considerations and probing techniques. For
more detailed information about differential measurements and common-mode
rejection ratio (CMRR), see the Reference section on page 9.
The P7360 Probe is optimized for high bandwidth; it is not a general purpose
probe. The probe head and tips are miniaturized for electrical characteristics and
access to dense circuitry, and must be handled carefully.
CAUTION. To prevent damage to the probe, use care when handling the probe.
Rough or careless use can damage the probe.
Input Voltage Limits
The P7360 Differential Probe is designed to probe low-voltage circuits. Before
probing a voltage, take into account the limits for maximum input voltage, the
common-mode signal range, and the differential-mode signal range. For specific
limits, refer to page 14.
Maximum Input Voltage
The maximum input voltage is the maximum voltage to ground that the inputs
can withstand without damaging the probe input circuitry.
CAUTION. To avoid damaging the inputs of the P7360 Differential Probe, do not
apply more than ±15 V (DC + peak AC) between each input or between either
probe input and ground.
The operating voltage window defines the maximum voltage that you can apply to
each input, with respect to earth ground, without saturating the probe input circuitry.
See Figure 1. A common-mode voltage that exceeds the operating voltage window
may produce an erroneous output waveform even when the diffe re ntia l-mode
specification is met. For specifications, refer to page 14.
The differential-mode signal range is the maximum voltage difference between
the plus and minus inputs that the probe can accept without distorting the signal.
The distortion from a voltage that is too large can result in a clipped or otherwise
inaccurate measurement. For specifications, refer to page 14.
1.3 V
+4.0 V
5X
25X
Figure 1: Dynamic range
Common-Mode Rejection
The common-mode rejection ratio (CMRR) is the ability of a probe to reject
signals that are common to both inputs. More precisely, CMRR is the ratio of the
differential gain to the common-mode gain. The higher the ratio, the greater the
ability to reject common-mode signals. CMRR varies with frequency, usually
decreasing at higher frequencies. F or additional information about CMRR, see
page 15.
Signal fidelity is an indication of how accurately a probe represents the signal
being measured. The signal fidelity of the probe is best when the probe is applied
directly to the circuit with the Short Flex, Small Resistor, Tip-Clip Assembly
shown in Figure 2. This Tip-Clip Assembly achieves high signal fidelity by
minimizing the distance between the probe head and the signal source. This
reduces probe interconnect parasitics which tend to degrade signal fidelity.
However, some probing tasks are made easier using other accessories included
with the probe.
The Tip-Clip specifications starting on page 18 show pulse response illustrations
that give some indication of signal fidelity with different Tip-Clip Assemblies.
Signal fidelity is affected by both the probe interconnect and the speed of the
signal. It is recommended that the longer the Tip-Clip Assembly be used with
somewhat slower speed signals for better signal fidelity.
Theory of Operation
Figure 2: Use the Short Flex, Small Resistor Tip-Clip Assembly
When you connect the probe inputs to a circuit, you are introducing a new
resistance, capacitance, and inductance into the circuit. Each input of the
differential probe has a characteristic input impedance of 50 kΩ to ground.
60 fF
3.12 pF
3.12 pF
60 fF
+
--
Input
Input
38 Ω
38 Ω
37 Ω
20 fF
20 fF
37 Ω
Cpl
Zodd=95
Zeven=190
L=3.7 mm
Kodd ~ Keven ~ 1
140 Ω
50 kΩ
310 Ω
310 Ω
50 kΩ
140 Ω
Figure 3: Typical probe input model
For signals with low source impedance and frequency, the 50 kΩ input impedance on each input is large enough to prevent the inputs from loading the signal
sources. As the signal source impedance on an input increases, the more the
probe loads the source and reduces the signal amplitude. The greater the source
impedances and the higher the signal frequencies, the more you must take these
factors into account. See Figure 3.
The frequency of the signal also affects signal measurement. As the frequency of
the signal increases, the input impedance of the probe decreases. The lower the
impedance of the probe relative to that of the source, the more the probe loads
the circuit under test and reduces the signal amplitude. For a graph of input
impedance versus frequency, refer to Figure 6 on page 15.
The Tip-Clip accessories included with your probe help connect to different
types of components. The Tip-Clip accessories are designed to provide optimum
performance as a system. Each Tip-Clip accessory has distinct characteristics.
While these accessories make connections easier, be aware that the Tip-Clip
accessory you choose affects the signal you are measuring, depending on a
variety of factors, including signal frequency, source impedance, and lead length.
Refer to Specifications on page 13 for more Tip-Clip information.
This section contains important reference information about differential
measurements and how to increase measurement accuracy.
Single-Ended Measurements
A differential probe, for example the P7360 Differential Probe, can be used for
single-ended measurements within the limits of its dynamic and offset voltage
ranges. Single-ended probes such as the P7240 typically have a wider offset
range than corresponding differential probes (see Table 1).
Table 1: Offset ranges
ProbeDC Offset, 5XDynamic
Range, 5X
P7240+/-- 5 V4V
P7360 Differential Probe
+4 V, --3 V1.25 V
PP
PP
DC Offset, 25XDynamic
Range, 25X
-- -- --
+4 V, --3 V5V
-- -- --
PP
Differential probes are ideal for a class of single-ended measurements where the
reference voltage is not ground:
HSSTL_1,2:V
HPECL:V
TT,VREF=VDD
REF=VCC
/2
--1.3
To measure single-ended signals in this class, connect the negative input of the
P7360 Differential Probe to V
REF
.
A differential probe in these applications displays the true signal despite any AC
or DC variation in V
displays the signal plus the variation in V
from its nominal value. While a single-ended probe
REF
.
REF
Differential probes can also be used to make ground referenced single-ended
measurements on either single-ended signals or differential signals like PCI Express or Serial ATA. To measure ground referenced single-ended signals, connect
the negative input of the P7360 Probe to ground.
Single-ended measurement on differential signals are used to measure common
mode voltage and check for differential signal symmetry.
A differential probe is optimized to make measurements of high speed differential signals. Differential signals are formed from two complementary signals with
a common reference voltage. See Figure 4.
Devices designed for differential measurements avoid problems presented by
single-ended systems. These devices include a variety of differential probes,
differential amplifiers, and isolators.
A differential probe is a differential amplifier (Figure 4), which is used to make
differential measurements that reject any voltage that is common to the inputs
and amplifies any difference between the inputs. Voltage that is common to both
inputs is often referred to as the Common-Mode Voltage (VCM) and voltage that
is different as the Differential-Mode Voltage (VDM).
Common-Mode Rejection
Ratio
Common
mode
V
CM
V
DM
2
+
V
DM
2
Differential
+
+
Differential
mode
mode
+
V
--
out
Figure 4: Simplified model of a differential amplifier
Differential amplifiers cannot reject all of the common-mode signal. The ability
of a differential amplifier to reject the common-mode signal is expressed as the
Common-Mode Rejection Ratio (CMRR). The CMRR is the differential-mode
gain (A
) divided by the common-mode gain (ACM). It is expressed either as a
DM
ratio or in dB.
A
DM
A
CM
CMRR =
A
DM
A
CM
dB = 20 log
10
CMRR generally is highest (best) at DC and degrades with increasing frequency.
Figure 5 on page 15 shows the CMRR of the P7360 Differential Probe. This
derating graph assumes a sinusoidal common-mode signal.
A quick way to assess the magnitude of CMRR error when the common-mode
signal is not sinusoidal is to connect both leads to the same point in the circuit.
The oscilloscope displays only the common-mode component that is not fully
rejected by the probe. While this technique may not give you accurate measurements, it does allow you to determine if the magnitude of the common-mode
error signal is significant. Make the probe Tip-Clip wires the same length to
maximize the probe CMRR.
The lower the input impedance of the probe relative to the source impedance, the
lower the CMRR for a given source impedance imbalance. Differences in the
source impedance driving the two inputs lowers the CMRR. Note that single-ended measurements generally result in asymmetric source impedances which tend
to reduce the differential mode CMRR.
The specifications in Tables 3 through 6 apply to the P7360 Differential Probe
installed on any TekConnect instrument or Tektronix 80A03 TekConnect adapter.
When the probe is used with another oscilloscope, the oscilloscope must have an
input impedance of 50 Ω. The probe must have a warm-up period of at least
20 minutes and be in an environment that does not exceed the limits described in
Table 3. Specifications for the P7360 Differential Probe fall into three categories:
warranted, typical, and nominal characteristics.
Warranted Characteristics
Warranted characteristics (Table 3) describe guaranteed performance within
tolerance limits or certain type-tested requirements. Warranted characteristics
that have checks in Table 3 are marked with the n symbol.
Table 3: Warranted electrical characteristics
CharacteristicDescription
n DC attenuation accuracy±2%
n Output Zero±3 mV (+20 to +30 _C, +68 to +86 _F) (5X) ±15 mV on oscilloscope
±3 mV (+20 to +30 _C, +68 to +86 _F) (25X) ±75 mV on oscilloscope
n Rise time<70 ps (probe only, Short Flex, Small Resistor Tip-Clip), all other Tip-Clip assemblies are
typical
TemperatureOperating: 0 to +40 _C (+32 to +104 _F),
Nonoperating: --55 to +75 _C (--131 to +167 _F)
HumidityOperating: 0--90% RH, tested at +0 to +40 _C (+32 to +104 _F)
Nonoperating: 0--90% RH, tested at --55 to +75 _ C (+67 to +167 _F)
1
See warning that follows.
1
WARNING. To avoid a burn hazard at high ambient temperatures, do not touch
the probe with bare hands at nonoperating temperatures above +75 _C
(+167 _F). Allow sufficient time for the probe to cool before handling.
Extended reach with good Step Response. Useful for connecting to hard to
reach small vias and fine-pitch circuitry.
Conveniently sized to fit between DIMM
modules. Not recommended for signals
faster than 4 GHz.
Extended reach with good step response.
Useful for connecting to hard-to-reach
circuitry with large features. Conveniently
sized to fit between DIMM modules. Not
recommended for signals faster than
4GHz.
The following procedures verify the warranted Output offset voltage, DC
attenuation accuracy, and Rise time specifications of the P7360 Differential
Probe. The recommended calibration interval is one year.
CAUTION. To avoid ESD damage to the probe, always use an antistatic
wrist strap (provided with your probe), and work at a static-approved
workstation when handling the probe.
Equipment Required
Table 7 lists the equipment required for the performance verification procedure.
The types and quantities of connectors depends on the specific equipment you
use.
Table 7: Test equipment
Description and quantityPerformance requirementRecommended example
Sampling OscilloscopeTektronix TDS 8200 Series
Sampling Module20 GHz bandwidthTektronix 80E04 or 80E03
Some of the adapters listed in Table 7 are available only from Tektronix. These
adapters are described on the following pages.
TekConnect-to-SMA
Adapter
Probe Calibration Fixture
The TekConnect-to-SMA Adapter, Tektronix part number TCA-SMA, lets you
connect an SMA cable to a TekConnect input. See Figure 8. Connect and
disconnect the adapter the same way as you do the probe.
This adapter is an oscilloscope accessory that can be used for measurement
applications, as well as these performance verification procedures.
Figure 8: TekConnect-to-SMA Adapter
Some of the procedures in this manual use a probe calibration fixture, Tektronix
part number 067-0419-XX.
The calibration fixture provides a means to test the probe for common mode
(CM) and differential mode (DM) measurements. SMA connectors on the front
and back of the fixture allow you to apply stimulus signals.
Some of the procedures in this manual use a PPM203B Articulated Arm. This is
a general purpose benchtop probe holder that provides a method for securing the
probe and must be used with the Probe Arm Adapter. Use the following steps
and Figure 10 to attach the Probe Arm Adapter to the PPM203B Articulated
Arm.
1. Using the Hex wrench, remove the screw from the end of the articulated arm.
2. Using the Hex wrench, attach the Adapter bottom to the probe arm.
3. Loosen the Adapter top by turning the two thumb screws counter clockwise.
4. Place the probe in the loosened Adapter bottom (keyed).
5. Secure the Adapter top by tightening the two thumb screws.
NOTE. Before beginning these procedures, refer to page 39 and photocopy the
test record (if you have not already done so) and use it to record the performance
test results.
Use the following procedure to test the Output Offset voltage.
1. Connect the equipment as shown in Figure 12.
2. Plug the probe into the 80A03 module and warm up for 20 minutes, if not
done.
3. Short the two Tip-Clip leads together (see Figure 12.) We recommend using
the BNC(m)-to-Minigrabber (black) with the Minigrabber not grounded.
This test checks the DC gain accuracy of the probe at the 5X and 25X attenuation settings.
Gain Check at 5X
Attenuation
1. Set the probe attenuation to 5X.
2. Connect the probe with a Tip-Clip Assembly to the power supply as shown
in Figure 13. Monitor the source voltage with one of the DMMs.
DMM (V in)
TDS/CSA 8200 Series Oscilloscope
+
--
Power supply
Banana
lead
Red
80A03
BNC-SMA
adapter
50 Ω Precision
termination
P7360 probe
Long Flex, Small
Tip-Clip Assembly
Banana
Black
--
+
Resistor, 1/8 W
BNC cable
lead
--+
--
Test leads (2),
w/mini plunger
BNC-to-dual
banana adapter
+
DMM (V out)
Figure 13: DC Gain Accuracy setup
3. Set the power supply to approximately +0.5 V. This represents 80% of the
probe dynamic range in this attenuation setting. Record this source voltage
1.
as V
in
4. Record the output voltage (on the second DMM) as V
5. Disconnect the test leads from the power supplies. Leave the DMM leads
connected to the adapters.
6. Reverse the polarity of the voltage applied to the probe inputs by swapping
both sets of banana leads at the power supply, as shown in Figure 14.
7. Record the actual source voltage (now a negative value), as V
This procedure verifies that the probe meets the rise time specification. Two rise
times are measured; the test system alone, and the test system with the probe
included. The probe rise time is calculated using the two measurements.
This test uses the TDR function of the 80E04 sampling head as a fast rise time
signal source. The measurements are made using an 80A03 TekConnect probe
interface. Although the following procedure assigns the TDR and measurement
functions to specific oscilloscope channels, any valid channel combination can
be used. However, the TDR function is only available on 80E04 sampling heads.
This test checks both of the probe attenuation settings.
Review Rise Time Measurements Using the Probe Calibration Fixture on
page 34 if you have not used a calibration fixture before.
1. Connect the fixture to the pulse generator using an SMA adapter.
2. Connect the 50
Ω termination included with the fixture to the unused SMA
connector.
3. Probe the calibration fixture using the Handheld Adapter (see Figure 16).
NOTE. It is recommended that you use the PPM203B Articulated Arm with the
Probe Arm Adapter (see page 28) to stabilize the probe while verifying the
differential rise time specification.
Signal
source
50 Ω
Termination
Figure 15: Handheld Adapter and calibration fixture
Figure 16: PPM203B Articulated Arm with the Handheld Adapter
1. Connect the standard 80A03 semi-rigid SMA connector between the 80A03
probe output and the 80E0X module input. Insert a TCA-SMA adapter into
the TekConnect interface on the 80A03.
2. Connect the test equipment as shown in Figure 17. A sampling module
extender cable is used with the TDR pulse generator to minimize cable loss
problems.
CAUTION. To prevent mechanical strain on the connectors, use care when
working with SMA connectors: Support equipment and use a torque wrench to
tighten connections to 7 in-lbs.
TDS/CSA 8000 Series Oscilloscope
CH 7 and 8 (module slot)
CH 4 (measurement
channel)
80A03
80E0X sampling
module
SMA male-to-male
connector
TCA-SMA adapter
SMA male-to-male
connector
Calibration fixture
80E04 TDR pulser
Sampling module extender cable
Figure 17: Test system rise time setup
NOTE. The 80A03 firmware version must be version V 2.0 or above. The
firmware version label is on the rear panel of the instrument.
3. Turn on Channel 4, and set the vertical scale to 50 mV/div.
4. Set the Channel 8 sampling head to TDR mode:
Press the SETUP DIALOGS button and select the TDR tab. See Figure 18.
TDR tab
Enable outputs
Preset
Step polarity
Figure 18: Setting the TDR parameters
5. Set the Preset of Channel 8. The sampling module turns on a red light next
to the SELECT channel button, indicating that TDR is activated for that
channel.
TDR Preset sets Internal Clock in the Trigger menu, turns on the TDR Step
in the TDR Setups menu, turns on the channel and selects the acquisition
units in the TDR Setups menu, and sets the horizontal scale, position, and
reference.
6. Turn off the display for Channels 8, then only Channel 4 is shown on the
screen.
7. Adjust the oscilloscope horizontal and vertical position controls to display a
signal similar to that shown in Figure 17.
8. Set the oscilloscope horizontal scale to 100 ps/div and center the waveform.
9. Use the oscilloscope measurement capability to display rise time. Increase
the stability of the pulse-edge measurement by using averaging, if available.
Rise time is measured from the 10% and 90% amplitude points on the
waveform. Rise time can be measured using the automatic measurement
capability of the TDS8200 series oscilloscopes. Record the system rise time
This value is used to calculate both the 5X and 25X probe rise times.
as t
s.
The following steps instruct you to assemble the test setup that includes the
probe, as shown in Figure 19. The system and probe rise time (t
measure in step 17 is used to calculate the probe rise time (t
10. Remove the calibration fixture from the TCA--SMA adapter and disconnect
the TCA--SMA adapter from the 80A03 TekConnect probe interface.
11. Connect the probe to the 80A03 TekConnect probe interface.
12. Check that an SMA 50
Ω termination included with the probe calibration
fixture is connected to the open SMA output on the fixture.
13. Set the attenuation on the probe to 25X.
14. Connect the probe input to the probe calibration fixture as shown in
Figure 16 on page 34. Check that the TDR function is still active.
The test setup should now be connected as shown in Figure 19.
15. Adjust the vertical scale to 50 mV/div, averaging on.
16. Expand the horizontal scale to help locate the step edge, then adjust the
horizontal range to 100 ps/div while centering the edge view. For a more
stable measurement display, turn averaging on.
17. Use the oscilloscope measurement capability to display rise time. Rise time
is measured from the 10% and 90% amplitude points on the waveform.
Record the rise time as t
s+p.
18. Calculate the probe rise time using the following formula:
2
Ꭹ
tp=t
(s+p)
− t
2
s
19. Record the calculated probe rise time on the test record.
Rise Time Check at 5X
Attenuation
38
20. Set the attenuation on the probe to 5X.
21. Repeat steps 16 through 19 for the 5X attenuation setting.
This section covers troubleshooting and probe maintenance.
Probe/Adapter/Oscilloscope Compatibility
The P7360 Differential Probe is designed to work with all TekConnect-interface
oscilloscopes and adapters. However, there may be some cases where probe
features may not work properly.
Table 8: Differential probe compatibility issues
SymptomLikely cause
P7360 Differential Probe does
not work with an 80A03 TekConnect Probe Interface
Adapter
The LED on the 80A03 Adapt er glows red, indicating an
incompatible probe.
The 80A03 Adapter requires firmware version 2.0 and above.
The firmware version label is on the rear panel of the
instrument. Contact Tektronix for information on updating the
adapter firmware.
Error Condition
Replacement Parts
The LEDs on the probe alert you to error or status conditions affecting the probe.
If the probe LEDs flash or otherwise appear to be malfunctioning, an error
condition may exist. Call your Tektronix representative for service.
When the probe is functioning correctly there is a quick flash of the LEDs on the
probe just after connecting to the oscilloscope.
There are no user replaceable parts within the probe. Refer to your product user
manual for a list of replaceable accessories for your probe.
If your probe does not meet the specifications tested in the Performance
Verification, you can send the probe to Tektronix for repair. F ollow the procedure
on page 42 to prevent damage to the probe during shipping.