Datasheet LT1016 (Analog Devices) - 9

HerstellerAnalog Devices
BeschreibungUltraFast Precision 10ns Comparator
Seiten / Seite22 / 9 — APPLICATIONS INFORMATION. Figure 4. LT1016 Response with Poor Bypassing. …
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DokumentenspracheEnglisch

APPLICATIONS INFORMATION. Figure 4. LT1016 Response with Poor Bypassing. Figure 5. Improper Probe Compensation Causes

APPLICATIONS INFORMATION Figure 4 LT1016 Response with Poor Bypassing Figure 5 Improper Probe Compensation Causes

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APPLICATIONS INFORMATION
In Figure 4 the LT1016’s supplies are bypassed, but it still in high speed circuits and can be quite confusing. It is oscillates. In this case, the bypass units are either too far not due to suspension of natural law, but is traceable to from the device or are lossy capacitors. Use capacitors with a grossly miscompensated or improperly selected oscil- good high frequency characteristics and mount them as loscope probe. Use probes that match your oscilloscope’s close as possible to the LT1016. An inch of wire between input characteristics and compensate them properly. the capacitor and the LT1016 can cause problems. If op- Figure 6 shows another probe-induced problem. Here, eration in the linear region is desired, the LT1016 must the amplitude seems correct but the 10ns response time be over a ground plate with good RF bypass capacitors LT1016 appears to have 50ns edges! In this case, the (≥0.01µF) having lead lengths less than 0.2 inches. Do probe used is too heavily compensated or slow for the not use sockets. oscilloscope. Never use 1× or “straight” probes. Their In Figure 5 the device is properly bypassed but a new bandwidth is 20MHz or less and capacitive loading is problem pops up. This photo shows both outputs of the high. Check probe bandwidth to ensure it is adequate for comparator. Trace A appears normal, but Trace B shows an the measurement. Similarly, use an oscilloscope with excursion of almost 8V—quite a trick for a device running adequate bandwidth. from a 5V supply. This is a commonly reported problem 2V/DIV 100ns/DIV 1016 F04
Figure 4. LT1016 Response with Poor Bypassing
TRACE A 2V/DIV 1V/DIV TRACE B 2V/DIV 10ns/DIV 1016 F05 50ns/DIV 1016 F06
Figure 5. Improper Probe Compensation Causes Figure 6. Overcompensated or Slow Probes Seemingly Unexplainable Amplitude Error Make Edges Look Too Slow
Rev D For more information www.analog.com 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Applications Information Typical Applications Appendix A Package Description Revision History Applications Information Related Parts