70 likes | 251 Views
Oscilloscope Probe Selection and Considerations . Lynsey Metz 12/10/13 EECS 713. Goal. Exploration of active versus passive oscilloscope probes and factors contributing to inaccurate measurements. Driving Factors: Probe capabilities Preserving measurement integrity Cost . Motivation.
E N D
Oscilloscope Probe Selection and Considerations Lynsey Metz 12/10/13 EECS 713
Goal Exploration of active versus passive oscilloscope probes and factors contributing to inaccurate measurements. Driving Factors: • Probe capabilities • Preserving measurement integrity • Cost
Motivation • Probes will interact with the circuit being tested, affecting the measurement • Rise time • Circuit loading • Inductance from ground lead • Reduced impedance at high frequency due to capacitance • Passive probe • Active probe with amplifier
Specs • Passive • Good up to 500 MHz • Cost ranges from fifteen to a few hundred dollars • Active
Test • Ideally, collect measurements from one high-frequency device using an active, passive, and shop-built 21:1 probe and compare results and verify active probe performance matched datasheet specs. • The shop-built 21:1 probe consists of a length of coaxial cable, a leaded 1k resistor, and some short ground lead. • No active probe available. Used a coaxial cable terminated in SMA and BNC connectors. • The device used for testing was a 150 MHz oscillator
Results (A) Coaxial cable (B) Passive probes (C) Shop-built Probe
References • Allen, C. (2013, Nov 19). HSD Test & Measurement, EECS 713, University of Kansas, Lawrence, KS. • Johnson. (1993). High speed digital design: A handbook of black magic. Pearson Education. • Change, Jae-yong,. 6 Hints for Better Scope Probing. Agilent Technologies.