Shmoo Plots
The Shmoo plot will be illustrated by measuring the
effect of power supply reduction on performance:
Nominally, a DUT operates at 1 Volt Vdd with 25 ns delay.
A set of test patterns is applied repeatedly to the DUT while sweeping:
- the output delay measured using the compare strobe:
sweeping variable Delay 1 from 20 ns to 30 ns (x-axis)
- the supply voltage Vdd:
sweeping variable DUT Power 1 from 0.8 Volts to 1.2 Volts (y-axis)
The expected result of the measurement is:
- For low supply voltages, the functional test will not pass.
- At a certain voltage, the DUT will pass functional test
at high delay times.
- Increasing voltage further, the DUT will operate faster.
Click to see the Shmoo plot