Delay Based Auto-Calibrated PVT Monitor System and Method

Abstract

In this paper, an auto-calibrated PVT (process, voltage, temperature) monitoring system based on delay chains and flip-flops is presented. The system and method are proposed to be used by IP's (Intellectual property) that require to monitor PVT conditions during its operation and depending on the detected changes be configurable or adaptive. The methodology is based on embedded PVT monitors that sense when the propagation delay variation in standard cells reaches a certain threshold. The system implementation is intended to be done since the RTL (register transfer level) design stage to avoid or reduce the full custom design effort. The PVT monitors are built using buffers from a technology design kit. The information of the PVT monitors is sent to a logic module that calibrates the monitors to choose the best monitoring option depending on the PVT corner, available clock, and standard cells delay. The system includes also a logic module that collects and sends the data inside or outside the chip, in parallel or serial modes. Characterization results of the PVT monitors are presented including different delay chains, and clock combinations trough different PVT corners. This system is intended to detect the change of the propagation delay in the cells due to the PVT conditions combined, and not to provide the stand-alone value of voltage, temperature, or process. Otherwise, one of the reasons for this proposal is to avoid the use of individual sensors.