Patent ID: 6871335

Claim:
A method of measuring signal skew of a signal tree on a programmable logic device, the signal tree having a source node connected to first and second destination branches, a first plurality of programmable logic blocks programmably connectable to the first destination branch, and a second plurality of programmable logic blocks programmably connectable to the second destination branch, each of the logic blocks having an input terminal and an output terminal, the method comprising: a. instantiating a first oscillator on the device using a first programming sequence that includes: i. connecting the first destination branch to the input terminal of one of the first plurality of logic blocks; ii. connecting the output terminal of the one of the first plurality of logic blocks to the input terminal of one of the second plurality of logic blocks; and iii. connecting the output terminal of the one of the second plurality of logic blocks to the source node; b. measuring the period the first oscillator; and c. instantiating a second oscillator on the device using a second programming sequence that includes: i. connecting the second destination branch to the input terminal of one of the second plurality of logic blocks; ii. connecting the output terminal of the one of the second plurality of logic blocks to the input terminal of a second one of the second plurality of logic blocks; and iii. connecting the output terminal of the second one of the second plurality of logic blocks to the source node; and d. measuring the period of the second oscillator.