N6457A

Oscilloscope Probes and Accessories Introduction To get the most out of your oscilloscope, you need the right probes and accessories for your particular applications. Whether you need the high bandwidth and low loading of an active probe, an easy way to connect to surface mount ICs or a passive probe to measure high voltages, there are a wide selection of high-quality probes and accessories for your Keysight Technologies, Inc. oscilloscope. Find us at www.keysight.com Page 1 How To Select A Probe Selecting the correct probe for your oscilloscope measurement should not be difficult. This brochure provides suggestions on how to make the best decision. Following is a list of probe parameters you need to consider when you select a probe for a given measurement. Attenuation Choose the attenuation ratio of the probe (1:1, 10:1, 100:1, 1000:1) to match the test signal amplitude to the oscilloscopes vertical sensitivity range. Higher attenuation probe allows the measurement range of a scope to be extended, and lower attenuation probe allows for lower noise measurement. Bandwidth (BW) The probes rated bandwidth should match the oscilloscopes and be adequate for the test signal. However, at higher frequencies, grounded lead inductance and input capacitance often influence system performance more than probe bandwidth. Input resistance (Rin) Input impedance is used to describe the loading effects of a probe. At DC and low frequency ranges, the probes resistive component is the main factor that loads down the circuit under test. However, as the frequency goes up, the capacitance of the probe tip, in parallel with the DC resistance, starts to reduce the input impedance of the probe, resulting in greater loading and a more adverse effect to the target. Input capacitance (Cin) Excessive input capacitance (sometimes called tip capacitance) slows down the systems pulse response. Usually the least input capacitance possible is best. Maximum input voltage (Vmax) To ensure user safety, help protect the oscilloscope input from destructive voltage, and avoid damage to the probe, select a probe that is rated for a higher voltage than the signal you intend to test. Probe compensation range Most passive probes have a specification that lists the oscilloscope input capacitance range over which they can be used. When choosing a passive probe, be sure that the oscilloscopes input capacitance lies within the probes compensation range or you will not be able to adjust the probe to achieve a correctly compensated square wave signal. Probe output termination Most oscilloscopes have 1-M and/or 50 input resistance. For proper signal transfer and optimum signal integrity, its important that the probes R and C match the R and C of the oscilloscope it is to be used with. For example, 50 terminated probes should be used with 50 scope inputs. Similarly, 1 M terminated probes should be used on scopes with a 1 M input resistance. Find us at www.keysight.com Page 2