Precision Jitter & Timing Tests in Milliseconds, in Parallel, in Production

As semiconductor manufacturers begin to implement high-speed, low voltage signaling in their next-generation graphics, memory, processor and communication devices, production ATE systems do not provide the capability to adequately test the critical timing parameters of these new high-speed devices. By utilizing the leading edge in Time Interval Analyzer technology, any digital or mixed-signal ATE system can perform precision jitter, risetime, skew and signal integrity testing cost-effectively in high-volume production.

Until recently, precision jitter and time measurements were not generally a required test parameters in production. At frequencies below 200MHz, timing margins are wide making it fairly easy to design circuits that control/tolerate a reasonable amount of jitter. Therefore, since jitter was not a major issue and since jitter test time at these lower frequencies would be too long for production, jitter and other timing tests were often omitted from the final test program.

However, the need for verifying timing parameters such as jitter, risetime, frequency and skew in video graphics, Ethernet and other high-speed devices is fast becoming an unavoidable reality. The need for timing tests in production today is largely due to the low yield and field failure problems that are increasingly being attributed to jitter and tight timing margins in these high-speed devices. But in order for these timing tests to be performed in production they must be accurate and fast.

The dilema most test engineers are now facing is that today’s ATE systems do not have the necessary functionality and/or performance to make these high-speed timing measurements in production. Specifically, the major challenges for today’s ATE systems are :

All of the above challenges for today’s ATE systems are easily addressed by the innovative use of a multi-channel Time Interval Analyzer (TIA).

Time Interval Analyzers (TIA) have the capability to make direct measurements of timing events relative to a measurement start time, T0. Direct time measurements with better than 30ps accuracy and 1ps resolution have been achieved using TIA technology. Careful input design results in an input measurement bandwidth of 2.3GHz or greater. This is important to ensure signal integrity is not influenced which would result in false results when making rise/fall time and jitter measurements. This high input bandwidth, combined with finely tuned interpolator contribute to the high measurement accuracy and resolution of Time Interval Analyzers.

In some ATE systems today, time measurements utilize a single channel Time Counter (TC) architecture which is inherently 25 to 30 times slower in measurement rate than Time Interval Analyzers (TIA). Currently available TIA instruments can make over one million measurements per second.

In addition to a much faster measurement rate, TIAs offer a unique feature which correlates each and every measurement to a master reference clock start time, T0. Time correlated measurements are extremely important to reduce the number of measurement points and the time required to measure/analyze timing characteristics such as frequency modulation and settling time.

The combining of several TIAs in a single instrument enables multi-site or parallel testing of many device outputs simultaneously. This parallel test capability, combined with the extremely fast measurement rate dramatically improves test time for jitter and other timing parameters in production.

In conclusion, ATE systems can be greatly enhanced to meet the requirements of high-speed jitter and timing tests by adding the functionality and performance of the latest TIA technology. Utilizing a TIA system with multiple channels and additional features such as analog waveform capture and differential inputs enables accurate jitter, timing and signal integrity tests in milliseconds, in parallel, in production.