Tektronix P7240 - page 29

OperatingBasics

P7240 4 GHz 5XAct ive Probe UserManual 19

Rsource

Vsource

ProbeC in

0.85pF

ProbeR in

20kΩ

Lgl(Ground Lead)

Figure 6: Ground Lead Equivalent Circuit

Ringing andrise time degradation can be masked if the frequency

content of the signal degradation is beyond the ba ndwidth of the

oscilloscope.

Youcan det ermine if ground lead effects may be a problem in your

application if you know the self-inductance (L ) and capacitance (C)

of your probe and ground lead. Calculate the approximate resonant

frequency (f0) at which this parasiticcircuit will resonate with the

following formula:

f0=1

2πLC



The preceding equation shows that reducing the ground le ad

inductance will raise the resonant frequency. If your measurements

are affected by ringing, your goal is to lower the induct ance of your

ground path until the resulting resonant frequency iswell above t he

frequency of your measurements.

The low-inductance ground contacts described in Features and

Accessories starting on page 5 can help you reduce the effects of

ground lead inductance on your measurements.

Contents

Main Page WARRANTY Page General Safety Summary ToAvoid Fire or Personal Injury Safety Termsand Symbols Table of Contents List of Figures Preface Related Manuals Contacting Tektronix Product Description TekConnectInterface Installation Page Page P7240 4 GHz 5XAct ive Probe UserManual 5 Features and Accessories Probe head assembly. TekConnectinterface Push-in probe tip (10 ea).Use the push-in 6P7240 4 GHz 5XAct ive Probe UserManual Installingthe push-in probe tip. SureToeprobe tip (4 ea).The SureToe tip is a SMT KlipChip (2 ea).Use the SMT KlipChip P7240 4 GHz 5XAct ive Probe UserManual 7 Y-leadadapter (2 ea). Three-inch ground lead (3 ea). 8P7240 4 GHz 5XAct ive Probe UserManual Customizable ground lead (5 ea) Adapter spring (10 ea). P7240 4 GHz 5XAct ive Probe UserManual 9 Low-inductance ground pogo pin (10 ea). Ground pin length adapter (10 ea). Cable marker bands (10 ea). 10 P7240 4 GHz 5XAct ive Probe UserManual Page 12 P7240 4 GHz 5XAct ive Probe UserManual Table2: P7240 optional accessories (Cont.) Functional Check Page Configuration Probe Offset Page Operating Basics Handling the Probe Maximum Nondestructive Input Voltage Input Linear Dynamic Range Ground Lead Length Page Page Helpful Hints Low-inductance Grounding SureFoot Grounding Appendix A: Specifications Specifications 24 P7240 4 GHz 5XAct ive Probe UserManual Table4: Typical electrical characteristics (Cont.) Figure 9: Typicalinput im pedance and phase versus frequency P7240 4 GHz 5XAct ive Probe UserManual 25 Gain =20 Log VOUT VIN Figure 11:Probe head and compensation box di mensions Figure 10: Typical bandwidth 26 P7240 4 GHz 5XAct ive Probe UserManual Table5: Physical Characteristics Table6: Environmental characteristics Appendix B: User Service Inspection and Cleaning Calibration Replacement Parts Preparation for Shipment Appendix C: Replaceable Parts Parts Ordering Information Using the Replaceable Parts List Page Page Appendix C: Replaceable Parts P7240 4 GHz 5XActive Probe User Manual 33 Page Appendix C: Replaceable Parts P7240 4 GHz 5XActive Probe User Manual 35