Pulse waveforms toggle between OFF state and ON state periodically. The following figure depicts an ideal trapezoidal pulse.

The pulse parameters (metrics) are measured as per the definitions of IEEE Std 181™-2011 (IEEE Standard on Transitions, Pulses, and Related Waveforms), from the IEEE Instrumentation and Measurement (I&M) Society.

Pulse metrics are categorized into two sections: time and level.

Pulse Time Metrics

Pulse time measures durations for different portions of the pulse.
  • The transition duration from OFF state to ON state is known as Rise Time and the transition duration from ON state to OFF state is known as Fall Time. The portion of transition duration used in calculating rise and fall time is determined by values you set in the Pulse Upper Threshold Level (%) and Pulse Lower Threshold Level (%) properties.
  • The duration for which the pulse remains in the ON state is known as the pulse width. The Pulse Width Threshold Level (%) property determines the pulse portion for pulse width calculation.

Pulse Level Metrics

Pulse level measures amplitude levels in different regions of the pulse.

Non-ideal pulses have characteristics such as overshoot, droop, and ripple. The following figure depicts a non-ideal pulse.



Overshoot

Overshoot is the ratio of the height of the local peak after a rising edge to the pulse amplitude.



Overshoot is calculated (either as a percentage or in dB) based on the value you set to the Pulse Amplitude Deviation Unit property. If you set the Pulse Amplitude Deviation Unit property to Percentage, then the overshoot value is calculated either in volts or watts based on the value you set in the Pulse Amplitude Level Domain property. The calculation is as follows:



where,

LOV is the peak level after rising edge

L100% is the ON level

L0% is the OFF level

Droop

Droop is the rate at which the pulse top levels decays from the beginning to the end during the ON duration.



For droop estimation, center 50% of the pulse ON duration samples are used. A best-fit linear line is applied on this region. The first point of intersection between the best fit line and the pulse is determined.

Droop is calculated (either as a percentage or in dB) based on the value you set to the Pulse Amplitude Deviation Unit property. If you set the Pulse Amplitude Deviation Unit property to Percentage, then the droop value is calculated either in volts or watts based on the value you set in the Pulse Amplitude Level Domain property. The calculation is as follows:



Lrise is the first point of intersection between the best-fit line and the pulse on the rising edge

Lfall is the first point of intersection between the best-fit line and the pulse on the falling edge

L100% is the ON level

L0% is the OFF level

Ripple

Ripple is the difference between the maximum and minimum deviation from the pulse top reference.



Ripple is calculated (either as a percentage or in dB) based on the value you set to the Pulse Amplitude Deviation Unit property. If you set the Pulse Amplitude Deviation Unit property to Percentage, then the ripple value is calculated either in volts or watts based on the value you set in the Pulse Amplitude Level Domain property. The calculation is as follows:



where,

Lrip+ is the maximum deviation from the pulse top above ON level

Lrip- is the maximum deviation from the pulse top below ON level

Ltop+ is the distance between Lrip+ and its projection on the linear best-fit line (calculated in the droop estimation)

Ltop- is the distance between Lrip- and its projection on the linear best-fit line (calculated in the droop estimation)

L100% is the ON level

L0% is the OFF level