Picotest P2104A Operator's manual

PDN Probes
Documentation
Version 1.54, August 2022
Copyright © 2014-2023 Picotest
All Rights Reserved

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The Picotest logo and “Picotest PDN Probes” are trademarks of Picotest Corp. PDN Cable
®is a registered trademark of Picotest Corp. All other brand and product names mentioned
herein are used for identification purposes only and are registered trademarks, trademarks, or
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Specifications are subject to change without notice.
Contact information
Corporate offices
1-877
914-PICO
Technical support e-mail
[email protected]
Declaration of conformity (EU)
The equipment adheres to the guidelines of the council of the European
Community for meeting the requirements of the member states regarding
the electromagnetic compatibility (EMC) directive and the RoHS directive.
Declaration of conformity (UK)
The equipment adheres to the regulations of the UK government for meeting
the requirements regarding the Electromagnetic Compatibility (EMC)
Regulation and the Regulation for Restriction of the Use of Certain Hazardous
Substances in Electrical and Electronic Equipment.
The PDN Cables are compliant with REACH EC 1907/2006.
Information for disposal and recycling
The Picotest Probes and Cables and all its accessories are not intended for household use. At the end
of its service life, do not dispose of the test set with household waste!
For customers in EU countries (incl. European Economic Area) Picotest test
sets are subject to the EU Waste Electrical and Electronic Equipment Directive
(WEEE directive). As part of our legal obligations under this legislation, Picotest
offers to take back the test set and to ensure that it is disposed of by an authorized
recycling facility.
For customers outside the European Economic Area
Please contact the authorities in charge for the relevant environmental regulations
in your country and dispose of Picotest products and all its accessories only in
accordance with your local legal requirements.

Table of Contents
Chapter 1 - Overview......................................................................................................4
Welcome ...........................................................................................................................................4
P2104A 1-Port Browser PDN Probe ...........................................................................................5
P2102A 2-Port Browser PDN Probe ...........................................................................................7
P2105A 1-Port Browser PDN Probe ...........................................................................................9
P2106A 1-Port Resistive Divider Probe.....................................................................................12
What’s Included with Your Probe ..............................................................................................14
Documentation and Support .......................................................................................................14
Warranty..........................................................................................................................................14
Chapter 2 –PDN Probes Usage ................................................................................... 15
Introduction....................................................................................................................................15
Connecting Your PDN Browser Probe to the Instrument and Making a Measurement ...16
Connecting Your P2105A TDR Probe to the J2154A TDR ..................................................20
Calibration.......................................................................................................................................21
DC Blockers: When and Why to Use Them .............................................................................22
NISM Stability Measurement (VRTS3 Board) ..........................................................................22
1-Port Probe Applications............................................................................................................25
Signal Injection – Jitter Testing using the J2150A (VRTS3 Board) .......................................25
Testing PCB Traces and Small values of Capacitance and Inductance .................................26
Testing Ripple ................................................................................................................................27
2-Port Probe Applications............................................................................................................28
Regulator Load Step Testing (VRTS3 Board) ...........................................................................28
Low Impedance PDN Power Integrity Testing (VRTS3 Board) ...........................................29
Chapter 3 – Accessories and Specifications................................................................. 31
Specifications..................................................................................................................................31
Safety Information.........................................................................................................................35
Handling Information...................................................................................................................36
Cleaning...........................................................................................................................................36

Overview 4
Chapter 1 - Overview
Welcome
Thank you for purchasing Picotest’s PDN ‘Browser’ probes.
The Picotest PDN probes are precision passive transmission line ‘Browser’ probes that
support a variety of measurements including impedance (1-Port Reflection and 2-Port Series
and Shunt-Through), 3-Port Voltage/Current, Step Load, Ripple, Noise, TDT/TDR, PCB
Resonances, Clock Jitter, and the Non-Invasive Stability Measurement (‘NISM’)123. The
probes have some significant advantages compared to active probes and other types of
passive probes.
The high-bandwidth, fixed-pitch probe tip design enables accurate measurements for a wide
variety of component and connector sizes. It eliminates the need for soldering SMA or coax
cables to your board and the risk of damaging fine copper pads or pulling up small
components. You can get connectivity to circuit boards and devices without connectors.
The probes can be used for ‘browser’ style measurement. For instance, if you have multiple
power rails across your board, the small form factor and easy probe tip placement enables
you to quickly browse the regulator outputs, allowing you to decide which rails need further
investigation. When coupled with NISM, you have a powerful tool for assessing the stability
of multiple power sources no matter the physical configuration.
1https://www.picotest.com/non-invasive-stability-measurement.html
2https://www.picotest.com/Power-Integrity-Book.html
3https://www.picotest.com/products_J202B.html

Overview 5
Impedance Measurement Demands New Probe Capabilities
High-speed applications put pressure on the measurement of power supply busses to
unprecedented frequencies. As an example, the measurement of PDN impedance for
FPGAs, ASICs, and high-speed digital devices generally requires the measurement of
impedance levels in the milliohm scale at frequencies exceeding 1GHz. Measuring the high-
speed step load response in power systems using 2-port impedance is difficult because of the
need to connect two 50Ω transmission lines to the output capacitor. To further compound
this difficult task, these measurements often need to be made in very small circuits such as
cell phones, solid state disk drives, and computer tablets, to name a few examples.
These revolutionary probes alleviate many of these challenges while maintaining the
precision 50Ω characteristics required for these types of measurements.
What is a Transmission Line Probe?
Transmission line probes are special types of passive probes that replace the high impedance
probe cable found in a traditional passive probe with a precision transmission line, that has a
characteristic impedance that matches the oscilloscope’s input (50Ω). This greatly reduces
the input capacitance to a fraction of a picofarad, minimizing the loading of high frequency
signals. The probes are referred to as ‘PDN’ probes, because of their effective use in
measuring the low and ultra-low impedances found in power distribution networks.
The input impedance of the Picotest probes remains nearly constant over their entire
frequency range. The probes are useful in applications that produce fast rising, narrow pulses
with amplitudes which exceed the dynamic range of active probes. They also tend to have
less parasitic effects on frequency response, so they are ideal for measuring impedance. By
providing a simple yet elegant and flexible solution to probing high-frequency signals,
Picotest’s transmission line probes preserve signal fidelity and allow high-bandwidth test
equipment to accurately measure circuit characteristics.\
P2104A 1-Port Browser PDN Probe
The P2104A 1-port probe is available in various probe tip spacings (50mil, 60mil, 70mil, and
100mil) allowing good connectivity to various component sizes. It also comes in one of four
attenuations (1X, 2X, 5X, or 10X). An AC coupled option providing DC blocking is also
available along with the 1X attenuation option. The probes are compatible with all
equipment including VNAs, oscilloscopes, and spectrum analyzers. Measurements of greater
than 100mohms, approximately, are possible. The range is not dependent on the probe, but
inherent in the 1-port reflection methodology.

Overview 6
Figure 1: P2104A 1-port probe
Figure 2: The P2104A 1-port probe comes in fixed pitch widths of 50, 60, 70, and 100mils. A
probe holder is a useful accessory.
P2104A 1-Port Probe Feature and Benefit Summary
•High bandwidth - > 6 GHz (uncorrected) Note: USABLE BANDWIDTH FOR
VNA WITH CALIBRATION IS HIGHER
•Virtually no capacitive loading (< 1pf, 420fF typical)
•Very flat frequency response (Impedance floor ~ 100mohms for 1-port reflection
impedance)

Overview 7
•Supports Browsing Measurement on Multiple Rails
oImpedance, Ripple, Noise TDT/TDR, 2 port impedance (using two P2104A
probes), PCB resonances, Clock Jitter and Non-invasive Stability
•Applications: Power Integrity, Power Electronics, Signal Integrity
•Available in various attenuations and pin pitches: Optimized for sensitivity and SNR
•Integrated series resistor option available for extended measurement range
•Integrated DC Block available for sensitive AC ripple/noise measurements or to
reduce DUT loading for impedance measurement.
•Use Two P2104A 1-Port Probes for High Bandwidth 2-Port Measurements
•Bi-directional – send signals to the DUT for signal injection or receive signals from
the DUT
•Use as a Browser accessory with Power Rail probes
•50 ohm impedance compatible with all 50 Ohm instruments
•Rugged, ergonomic design, small form factor gets into tight places
•Slim body with spring tips provides good visibility of the target and reliable
connectivity
•Uses PDN Cable ® for optimum performance
•Includes P2100A CAL Calibration Board for SOLT and ISOLATION calibration
•Supports NISM - Non-Invasive Stability Measurement for Phase Margin Testing
P2102A 2-Port Browser PDN Probe
The P2102A 2-port probe comes with four (4) interchangeable, snap on, probe heads sizes
(1206, 0805, 0603, and 0402) allowing good connectivity to various component sizes. It also
comes in one of four attenuations (1X, 2X, 5X, or 10X). An AC coupled option providing
DC blocking is also available along with the 1X attenuation option.

Overview 8
Figure 3: P2102A 2-port probe.
The probes are compatible with all equipment including VNAs, oscilloscopes, and spectrum
analyzers.
The P2102A probe is designed to work with the J2102B common mode transformer, or the
J2113A ground loop isolator, which eliminates instrument DC ground loops in low
impedance measurements.
P2102A 2-Port Probe Feature and Benefit Summary
•Supports Measuring:
Impedance, Transient Step Load, Ripple, Noise, 2-port impedance, PCB
resonances, Clock Jitter, and Non-invasive Stability
•Wide Bandwidth – 300MHz *
•Measures < 1mOhm *, Up to kOhms **
•Four (4) Interchangeable Probe Heads –- Sizes 1206, 0805, 0603, and 0402

Overview 9
•Various Attenuations – 1X for optimum sensitivity and SNR, 2X, 5X, and 10X.
Higher attenuation is for higher voltages, impedance, or reduced loading
•True 4-Point Kelvin Measurement
•Browsing capability greatly eases testing of multiple rails and repeat measurements
•Virtually no capacitive loading
•Includes PDN Cables® for ultra-high shield attenuation and ultra-low shield
resistance
•Rugged, ergonomic design; small form factor gets into tight places
•Supports Non-Invasive Stability Measurement (NISM)
•Supports the Extended Range 2-Port Shunt-Through measurement
* Calibration dependent
** Using the EXTENDED 2-port setup.
P2105A 1-Port Browser PDN Probe
The Picotest P2105A probe is 50 ohm 1-port transmission line 'Browser' probe for TDR
applications. This precision probe supports a variety of measurements using the 1-port
reflection methodology including primarily impedance and TDT/TDR, but also ripple,
noise, PCB power rail, VRM (Voltage Regulator Module), and clock jitter. It has significant
advantages in comparison to active probes and other types of passive probes.
The P2105A is referred to as a 'browser' probe for its ability to quickly and easily be moved
from point-to-point/rail-to-rail simply by reseating the probe points. The probe achieves a
very low inductance at the tip to mitigate space constraints on a dense PCB, while
eliminating the need to add additional SMA connections or other test points necessary for
impedance measurements. It is especially useful when there are multiple rails to assess and
there is not time or PCB iterations available to provide test point implementations for each.
Repeated measurements are simplified because connection is by simply touching the tip to
existing trace. The P2105A is available in four fixed pin pitches (31, 40, 50, 60 mil spacing
with 1X attenuation).
The probe is compatible with all 50 ohm instruments, including the J2154A PerfectPulse
TDR, vector network analyzers (VNAs), oscilloscopes, and spectrum analyzers. The probe is
designed to work with the traditional single ended TDR setup.
The center pin is always signal and provides a reference using the probe tip label side. When
used with a TDR, getting it backwards won’t normally result in any damage. The P2104A
and P2105A can do damage if connected backwards to an active power rail.

Overview 10
Figure 4: P2105A TDR probe. The P2105A 1-port probe comes in fixed pitch widths of 31, 40,
50, 60, 70, 100mils and GSG SMA. Custom pitches are also available.

Overview 11
Figure 5: The P2105A TDR probe with the J2154A PerfectPulse TDR. A probe holder is a
useful accessory.
P2105A 1-Port Probe Feature and Benefit Summary
•15GHz Single-Ended Precise High Bandwidth Probe for all Time Domain
Reflectometry (TDR) Applications
•Compatible with the Picotest J2154A PerfectPulse TDR
•Fixed pitches available: 31, 40, 50, 60, 70, 100 mils and GSG SMA
•Compatible with all 50 ohm Instruments
•Spring pins for easy landing
•Short pins and integrated, but removable, PDN cable for low coupling and optimum
shielding
•Handheld browser style for repeatable and easy probing; Handle design fits most
probe holders
•Slim low-profile housing for comfort and visibility

Overview 12
Applications *
•Low-cost PCB coupon tester - Characteristic Impedance PCB traces
•Measure PCB trace length, characteristic impedance, and dielectric constant
•Locate and detect impedance mismatches
•Measure parasitic values of inductance and capacitance such as bond wires, vias, and
ESL
•Measure PCB trace path rise/fall time and overshoot/undershoot
•Supports cable and trace loss modeling
* When coupled with the J2154A TDR.
P2106A 1-Port Resistive Divider Probe
The Picotest P2106A probe is a high impedance voltage divider ‘Browser’ probe, specifically
designed to be low bandwidth and resonance free. When paired with the Picotest J2180A
low noise amplifier and PDN cable, the low noise measurement can be connected directly to
any 50 Ohm instrument, including signal source analyzers, spectrum analyzers, and low-
noise oscilloscopes. The P2106A provides one of the lowest noise floor testing solutions
allowing measurement of sensitive power supplies for power amplifiers and
telecommunications equipment up to 65V.
The bottom resistor is typically 1K and the tip resistor sets the attenuation. The P2106A-
20K-20X has approximately a 19K tip resistor and 1K bottom resistor. This ~1kOhm
Thevenin impedance forms a low pass filter with the coaxial cable (30pF/ft) and the J2180A
low noise preamplifier input capacitance (~36pF) (Fbw=1/(2*PI*1k*125pF)=1.2MHz.
There is essentially zero capacitance at the probe tip. The general application is to connect a
relatively High Z, uncompensated probe to the J2180A amplifier for the purpose of getting a
low noise, low bandwidth signal to a 50 Ohm instrument.
The P2106A is available in fixed pin pitches of 50, 60, or 100mils. The P2106A probe can be
purchased in almost any desired attenuation (1:1, 20:1 and User-Defined Attenuations
Variable Resistance including 20kOhm). Using an uncompensated voltage divider results in
near zero capacitance and is assured to be resonance free for accurate measurement with
minimal loading. The uncompensated divider results in a low bandwidth measurement, set
primarily by the coaxial cable and J2180A preamplifier capacitance.
P2106A 1-Port Probe Feature and Benefit Summary
•Available in custom attenuations and resistance levels
•Bandwidth – Typically 1-2 MHz
•Low loading, uncompensated assures no peaking
•Supports low noise measurement
•Couples to J2180A preamplifier to reduce noise, convert to 50 Ohm instrument

Overview 13
compatibility
•Available in various attenuations and pin pitches: Optimized for SNR
•Virtually no capacitive loading (< 1pf, 420fF typical)
•Rugged, ergonomic design, small form factor gets into tight places
•Slim body with spring tips provides good visibility of the target and reliable
connectivity
•Uses PDN Cable ® for optimum performance

Overview 14
What’s Included with Your Probe
Your Picotest Probe kit (P2104A) includes the following:
•1-Port Probe with PDN Cables
•P2100A-CAL probe calibrator board
•Probe Case
Your Picotest Probe kit (P2102A) includes the following:
•2-Port Probe with PDN Cables
•P2100A-CAL probe calibrator board
•Probe Case
Your Picotest Probe kit (P2105A) includes the following:
•TDR Probe with PDN Cables
•TDR Demo Board
•Probe Case
Your Picotest Probe kit (P2106A) includes the following:
•1-Port Probe with PDN Cable
•P2100A-CAL probe calibrator board
•Probe Case
Documentation and Support
This documentation details the use of various probes. Specifications for the individual
probes are also included. The support section of Picotest’s web site,
https://www.picotest.com/support.html, contains additional documentation and various
publications on testing power supplies, regulators, and other equipment using the Picotest
probes.
Warranty
Every Picotest product you buy from Picotest.com is backed by a 1-year manufacturer’s
warranty. For warranty service or repair this product must be returned to a service facility
designated by PICOTEST. Please contact your local service representative for further
assistance.

PDN Probes 15
Chapter 2 –PDN Probes Usage
Introduction
The PDN probes have a wide dynamic range and can measure up to various voltage levels
without distortion (see specifications table for the voltage ranges for different attenuations).
The low inherent noise enables the measurement of small input signals. The P2104A and the
P2102A may be used with any 50 Ohm instrument. Both are bi-directional and can be used
like a traditional probe to record signals, as well as to inject stimulus (load step currents or
EMI). The probes are especially useful for VRM/stability measurements.
Usage notes:
•Variable pin compression means variable inductance and coupling. It is
recommended that the same pressure/pin depression be used for calibration and
actual testing. There may be an uncertainty of 100-200 pH.
•The resistors on the calibrator board are all 49.9 Ohms. Very small resistors are used
to stay out of the way of the pins and to present minimum parasitic inductance.
•The 2-port SOLT fixture removal calibration works well for low impedance testing.
Consult your VNA’s or oscilloscope’s user manual for details on performing probe
calibration.
•Full 2-port calibration with isolation is important if you want measure inductance
values below a few nH.

PDN Probes 16
•Typical cable markers are placed on the cables/probe head for identifying the ports
and the probe head has an indent in the housing for the tip side while the ground
side is flat and smooth.
•It is recommended that the pads used for testing be oversized by 20% if possible, to
make it easier to land the probe. For instance, the calibrator pads are about 20%
oversized.
•Two 1-port P2104A probes are generally better than one 2-port P2102A probe for
coupling and pin length, but harder to use and generally require probe holders to fix
the relative angle. One of the issues with using two 1-port probes is they should be
calibrated at a particular angle and separation distance. Once they are calibrated, the
same exact distance and angle need to be used for the measurement. A second issue
is that if they get too far apart, you end up with transimpedance and not self-
impedance. Two upsides are that they can be used to measure from both sides of the
board (ideal plane impedance from a pair of vias) or perpendicular for less coupling.
A big upside to the 2-port probe is that while there is coupling, it is fixed and so
doesn’t require the same precision for placement / measurement.
•Excessive pressure on the pins can damage the pin springs leaving the pin stuck in a
depressed state. The pins can be replaced at the factory, but it is recommended that
you avoid excessive pressure on the probe tips.
Connecting Your PDN Browser Probe to the Instrument and
Making a Measurement
To connect your PDN Browser probe, connect the SMA connector of the probe to the
SMA connector on the instrument. If the instrument has a BNC connector, then a SMA to
BNC adapter is required.
For measurements on most instruments, configure the settings as follows:
•Input impedance of the channel = 50 Ω
•Unit = V
•Attenuation = 1:1 (for the 1x probe)
Note: Not all instruments will handle this the same way. Instruments that accept the
extended range 4just want to know the tip resistor. Other instruments might want the
attenuation.
4“The Simple Truth about Complex Impedance Probes”, Apr 19, 2022,
https://www.youtube.com/watch?v=HFTd7pH06s4

PDN Probes 17
You can now place the signal and ground pins on the target measurement points in your
circuit.
The probe consists of the probe head for connection to the DUT, the probe cable, and SMA
connector(s). The 2-port probe has two SMA connectors, one for each port with a common
ground.
The probes have standard SMA connectors on each port.
For the P2102A, the positive pins/signals are on the side with the label.
For the P2104A and the P2105A, the positive pin/signal is the pin in the center.
Figure 6: A 2-port measurement using the P2102A probe. Pressure is needed to seat the four
pins firmly in place. The probe head should match or be larger than the capacitor you are
measuring across. Two pins go on each side of the capacitor.

PDN Probes 18
Figure 7: Two signal lines go on the positive side of the capacitor and two ground lines go
on the ground side of the capacitor. The positive probe side is the side with the label.

PDN Probes 19
Figure 8: A 2-port measurement using a probe holder which can help supply even pressure
for the four pins.

PDN Probes 20
Figure 9: The center pin is the positive pin on the P2104 q-port probe.
Connecting Your P2105A TDR Probe to the J2154A TDR
For more information on connecting and using your P2105A TDR probe, please see
the J2154A Differential TDR manual.