A Built-In Self-Test scheme for high speed I/O using cycle-by-cycle edge control

This paper presents a Built-In Self-Test (BIST) circuit for high speed I/O, based on an embedded pattern generator to remove external factors which could affect the I/O parameters. The rising and falling edge positions of the generated patterns can be controlled independently during every cycle. In the basic operation mode, ATE provides the codes for controlling the edge positions, while in extended mode, an embedded counter generates the control codes. The control of both rising and falling edges makes this scheme especially good for systems with Double-Data Rate (DDR) interfaces. Moreover, the cycle-by-cycle control allows us to analyze efficiently the influence of mismatch trees and per-pin skew on I/O performance. The proposed BIST circuit has been simulated using a 0.18-μm process.