A Built-In Self-Test scheme for DDR memory output timing test and measurement

Abstract

This paper presents a Built-In Self-Test (BIST) scheme to measure high speed double data rate (DDR) memory output timing using low cost testers. This technique uses an onchip pattern generator to generate a time delay between data and data-strobe or clock. The time delay is controlled precisely using a phase interpolator based cycle-by-cycle control method. A novel method for testing the resolution of phase interpolator, which does not need any extra hardware, is also presented. Using the test resolution, a timing pass/fail flag is set and the timing margin is quantified as a multiple of the test clock cycle. Since these test results have high observability, output per-pin timing performance can be diagnosed easily, which is especially good for testing parallel memory interfaces. Moreover, these features make our scheme compatible with low-cost testers and decreases the time-to-market for the chip. The BIST circuit has been implemented using the 0.18-µm CMOS process, and chip measurement results are presented. We obtained a test resolution of 10 ps for testing output timing. Using the fabricated test chip, this paper shows the effects of switching noise, per-pin skews and slew-rate change on output timing variations.

A universal automatic on-chip measurement of FPGA’s internal setup and hold times

“…Unable to directly access the Module Under Test (MUT) inside the chip, ATE can only access the MUT via I/Os. This invites inaccuracy problems due to external test environment factors, such as impedance mismatch and heavy capacitive load [9].…”

An FPGA-based ATE extension module for low-cost multi-GHz memory test

“…ATE systems and extensions [3] provide the ability of multi-channel and high-speed testing. Built-In Self-Test (BIST) [4,5] is another way to test memory. In this scheme, BIST uses low-speed signals from an ATE system and generates highspeed data for memory testing within the DUT.…”

Real-Time Testing Method for Multilevel Signal Interfaces and Its Impact on Test Cost

“…Even though, many studies of high-speed interface testing methods have been conducted [4]- [6], these methods are developed only for testing binary signal. No real-time testing solution for the multilevel signals has been released at this time.…”