The Double Exponential Pulse

 

The Double Exponential Pulse

The waveform of an electrostatic discharge current has a 10 to 90 percent rise time of perhaps 150 ps to a peak amplitude of perhaps 10 Amperes, then falling off gradually with time.^[12] The length of the pulse, as measured at the two 50-percent points, may be 150 ns. The discharge can be modeled as a double exponential pulse of the form^[13]

where:

• S is a scaling (amplitude) constant

• a and b (with a < b) are two modeling parameters that define the shape of the pulse

For a typical ESD event, a is in the tens of MHz, and b is in the tens of GHz.