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:

1. For low supply voltages, the functional test will not pass.
2. At a certain voltage, the DUT will pass functional test at high delay times.
3. Increasing voltage further, the DUT will operate faster.

Click to see the Shmoo plot