OVERSHOOT CONTROL FOR 2 COUPLED RLC INTERCONNECTIONS

An algorithm is introduced to upgrade package performance for two coup led lines. A compromise between fast response and limited undershoot i s based upon a 4% overshoot control condition. It is easy to use this time domain requirement because it can be applied to the transfer func tion in the frequency domain. In the frequency domain, it is known tha t a low-frequency approximation to the transfer function provides a si mple and accurate trade-off requirement for single-mode overshoot cont rol. For mixed mode, i.e. for the case of one driven line and one quie t line, it is shown here that the same approximation can be used to co ntrol the overshoot in the weak coupling case. A closed-form relations hip among electrical line and termination parameters results. However, for strong coupling (small line spacing), the time domain transient r esponse with parameters based on the closed-form relationship is inacc urate. For strong coupling it is shown here an average-transfer-functi on (ATF) method can be used for calculating trade-offs when multiple m odes are excited.