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This article explores the pulse response of 3 CDM test heads by measuring CDM current sensors using two 1-meter long coax cables. The risetime, bandwidth, and ringing characteristics of various CDM current sensors are compared to identify the most accurate and reliable measurements for CDM designers.
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Pulse Response of 3 CDM Test Head • Three CDM current sensors Measured using two ea. 1 meter long coax cables • System 39 ps Risetime • BEI 43 ps Risetime, 18 GHz bandwidth • ESDA 33 ps Risetime, 16 GHz ringing June 8, 2012 Jon Barth
Time Domain Pulse Response 6 GHz Scope and two 1 Meter Coax Cables
3 CDM Test Head Discharge Waveforms • CDM discharge waveforms made on RCDM 3 tester • Discharge from Special BEI flat surface JEDEC coins of standard diameters • 6 GHz Tektronix scope • 37 degrees F Dew Point
500 Volt Small BEI Coin BEI ESDA JEDEC
Impulse Comparison of 3 CDM Current Sensors 1 GHz Bandwidth
Impulse Comparison 3 GHz bandwidth
Impulse Comparison 6 GHz bandwidth
ESDA-JEDEC CDM Current Sensors • Equal response at 1 GHz • Different at 3 GHz • Very different responses at 6 GHz • BEI 5A Current sensor • Wide bandwidth • Flat response • Accurate measurements for CDM designers
Requirements for a Repeatable Standard • Each current sensor to be measured individually • Evaluating current sensors in the CDM system includes many variables • The Barth Model 5A current sensor is measured individually