Methods for determining a maximum operating frequency for TTL gates

Abstract

Two methods for determining a realistic maximum operating frequency for TTL gates are developed. Both methods involve using propagation delay times and redefining them to valid TTL levels. The first method is a rigorous treatment of the subject, while the second is an easy-to-use rule of thumb. The exponential-linear method, which is extensively discussed, is slightly conservative. No devices tested during this study would have failed due to the maximum operating frequency (f/sub MAX/) computed using this technique. The linear-linear technique is less conservative; several devices in this study would have failed to meet f/sub MAX/ requirements had this technique been used.<>