Differential Probes Enable Nanosecond-Order High Frequency Analysis

February 1st, 2008

Denso Corporation has begun using high-voltage, differential probes to analyze nanosecond transient noise spikes in its Electronic Control Units (ECUs) for engine control.

Operational conditions and requirements for these units have become increasingly stringent in recent years. Similarly, demand for the ability to analyze higher frequencies has escalated, particularly with regard to noise immunity to transient signals or spikes in the millisecond or microsecond, and most recently at the nanosecond level. However, analysis of high-frequency noise in the order of nanoseconds with conventional oscilloscopes and probes had been problematic because of the presence of extremely noisy waveforms.

To address this challenge, Tektronix developed probes that reduce the electrical load on the measurement system, including the probe. Although the passive voltage probes being used previously were simple to use, input capacitance was quite large, and this distorted the waveform being measured. To correct for this, Denso used the TDP1000 Active High Voltage Differential Probe. The differential input capacitance of the probe is less than 1pF, so any influence of the measuring instruments on the measurement is minimal.

Another key feature is that differential inputs minimize the effects of common mode noise. This makes it possible to reduce the amount of time it takes to analyze a signal from microseconds to nanoseconds. This has enabled Denso to view signal line waveforms, including lines that have nanosecond-order high-frequency noise. This is an extremely significant achievement that will result in enhanced ECU quality and reliability.

Entry Filed under: Electronics Test